arm64: Makefile: Remove "-z norelro" from vmlinux ldflags

* This spams warnings
* aarch64-linux-gnu-ld: warning: -z norelro ignored

Signed-off-by: nishant6342 <www.rajsonu13@gmail.com>
Signed-off-by: Cykeek <Cykeek@proton.me>
Signed-off-by: improbir <ghosh_probir@yahoo.com>