Specify options_file in vendor_ramdisk prebuilt_kernel module

To install module.options file to the vendor_ramdisk partition

Test: m soong_generated_vendor_ramdisk_filesystem_test
Bug: 381104942
Change-Id: I872a2100ce72171394731e6295fa4d1a611a3f4f
diff --git a/android/variable.go b/android/variable.go
index 50d1fcd..25d99da 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -664,6 +664,7 @@
 	VendorRamdiskKernelModules       []string `json:",omitempty"`
 	VendorRamdiskKernelBlocklistFile string   `json:",omitempty"`
 	VendorRamdiskKernelLoadModules   []string `json:",omitempty"`
+	VendorRamdiskKernelOptionsFile   string   `json:",omitempty"`
 }
 
 func boolPtr(v bool) *bool {