Enable crypto extensions for armv9-a

It's not enabled by default for ARMv9-A targets on LLVM.
But most, if not all, of the ARMv9-A CPUs do support it.

Ref: llvm/llvm-project@f576cbe
Shoutout to Jake for noticing.

Change-Id: I5d900df45de9d843546ab2c0a9537eb79662be4a
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>

cc/config/arm64_device.go

@@ -42,7 +42,7 @@ var (
 			"-march=armv8.2-a+lse+fp16+dotprod",
 		},
 		"armv9-a": []string{
-			"-march=armv9-a+nosve",
+			"-march=armv9-a+crypto+nosve",
 			"-mbranch-protection=standard",
 			"-fno-stack-protector",
 		},