Update soong to use flag for min supported sdk

Test: Build and flash
Test: adb shell getprop ro.build.version.min_supported_target_sdk
Bug: 297603927
Change-Id: I5123c58c8397ae44f163c2c2ee557dce9b0437c1
diff --git a/android/variable.go b/android/variable.go
index 5a079db..0040d83 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -201,23 +201,22 @@
 	BuildThumbprintFile *string `json:",omitempty"`
 	DisplayBuildNumber  *bool   `json:",omitempty"`
 
-	Platform_display_version_name             *string  `json:",omitempty"`
-	Platform_version_name                     *string  `json:",omitempty"`
-	Platform_sdk_version                      *int     `json:",omitempty"`
-	Platform_sdk_codename                     *string  `json:",omitempty"`
-	Platform_sdk_version_or_codename          *string  `json:",omitempty"`
-	Platform_sdk_final                        *bool    `json:",omitempty"`
-	Platform_sdk_extension_version            *int     `json:",omitempty"`
-	Platform_base_sdk_extension_version       *int     `json:",omitempty"`
-	Platform_version_active_codenames         []string `json:",omitempty"`
-	Platform_version_all_preview_codenames    []string `json:",omitempty"`
-	Platform_systemsdk_versions               []string `json:",omitempty"`
-	Platform_security_patch                   *string  `json:",omitempty"`
-	Platform_preview_sdk_version              *string  `json:",omitempty"`
-	Platform_min_supported_target_sdk_version *string  `json:",omitempty"`
-	Platform_base_os                          *string  `json:",omitempty"`
-	Platform_version_last_stable              *string  `json:",omitempty"`
-	Platform_version_known_codenames          *string  `json:",omitempty"`
+	Platform_display_version_name          *string  `json:",omitempty"`
+	Platform_version_name                  *string  `json:",omitempty"`
+	Platform_sdk_version                   *int     `json:",omitempty"`
+	Platform_sdk_codename                  *string  `json:",omitempty"`
+	Platform_sdk_version_or_codename       *string  `json:",omitempty"`
+	Platform_sdk_final                     *bool    `json:",omitempty"`
+	Platform_sdk_extension_version         *int     `json:",omitempty"`
+	Platform_base_sdk_extension_version    *int     `json:",omitempty"`
+	Platform_version_active_codenames      []string `json:",omitempty"`
+	Platform_version_all_preview_codenames []string `json:",omitempty"`
+	Platform_systemsdk_versions            []string `json:",omitempty"`
+	Platform_security_patch                *string  `json:",omitempty"`
+	Platform_preview_sdk_version           *string  `json:",omitempty"`
+	Platform_base_os                       *string  `json:",omitempty"`
+	Platform_version_last_stable           *string  `json:",omitempty"`
+	Platform_version_known_codenames       *string  `json:",omitempty"`
 
 	DeviceName                            *string  `json:",omitempty"`
 	DeviceProduct                         *string  `json:",omitempty"`