arm64: unnecessary end 'return;' in void functions

The end 'return;' in a void function is useless and verbose. It can
be removed safely.
Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
Link: https://lore.kernel.org/r/20210726123940.63232-1-wangborong@cdjrlc.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/cpufeature.c

@@ -1561,8 +1561,6 @@ kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused)
 
 	if (!cpu)
 		arm64_use_ng_mappings = true;
-
-	return;
 }
 #else
 static void