crypto: arm64 - Fix unused variable compilation warnings of cpu_feature

The cpu feature defined by MODULE_DEVICE_TABLE is only referenced when
compiling as a module, and the warning of unused variable will be
encountered when compiling with intree. The warning can be removed by
adding the __maybe_unused flag.

Fixes: 03c9a333 ("crypto: arm64/ghash - add NEON accelerated fallback for 64-bit PMULL")
Fixes: ae1b83c7 ("crypto: arm64/sm4 - add CE implementation for GCM mode")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

arch/arm64/crypto/ghash-ce-glue.c

@@ -508,7 +508,7 @@ static void __exit ghash_ce_mod_exit(void)
 		crypto_unregister_shash(&ghash_alg);
 }
 
-static const struct cpu_feature ghash_cpu_feature[] = {
+static const struct cpu_feature __maybe_unused ghash_cpu_feature[] = {
 	{ cpu_feature(PMULL) }, { }
 };
 MODULE_DEVICE_TABLE(cpu, ghash_cpu_feature);

arch/arm64/crypto/sm4-ce-gcm-glue.c

@@ -271,7 +271,7 @@ static void __exit sm4_ce_gcm_exit(void)
 	crypto_unregister_aead(&sm4_gcm_alg);
 }
 
-static const struct cpu_feature sm4_ce_gcm_cpu_feature[] = {
+static const struct cpu_feature __maybe_unused sm4_ce_gcm_cpu_feature[] = {
 	{ cpu_feature(PMULL) },
 	{}
 };