Add ARMv9.2-A support for Rust.

Bug: 364383722
Test: presubmit, internal build for relevant device
Change-Id: I6e9db98fa2b31349484f83baef612527fbe7c15a
diff --git a/rust/config/arm64_device.go b/rust/config/arm64_device.go
index 9850570..94a4457 100644
--- a/rust/config/arm64_device.go
+++ b/rust/config/arm64_device.go
@@ -35,8 +35,13 @@
 		},
 		"armv8-2a":         []string{},
 		"armv8-2a-dotprod": []string{},
+
+		// branch-protection=bti,pac-ret is equivalent to Clang's mbranch-protection=standard
 		"armv9-a": []string{
-			// branch-protection=bti,pac-ret is equivalent to Clang's mbranch-protection=standard
+			"-Z branch-protection=bti,pac-ret",
+			"-Z stack-protector=none",
+		},
+		"armv9-2a": []string{
 			"-Z branch-protection=bti,pac-ret",
 			"-Z stack-protector=none",
 		},