crypto/arm64: aes-ce-gcm - add missing kernel_neon_begin/end pair

Calling pmull_gcm_encrypt_block() requires kernel_neon_begin() and
kernel_neon_end() to be used since the routine touches the NEON
register file. Add the missing calls.

Also, since NEON register contents are not preserved outside of
a kernel mode NEON region, pass the key schedule array again.

Fixes: 7c50136a8aba ("crypto: arm64/aes-ghash - yield NEON after every ...")
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

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

@@ -488,9 +488,13 @@ static int gcm_decrypt(struct aead_request *req)
 			err = skcipher_walk_done(&walk,
 						 walk.nbytes % AES_BLOCK_SIZE);
 		}
-		if (walk.nbytes)
-			pmull_gcm_encrypt_block(iv, iv, NULL,
+		if (walk.nbytes) {
+			kernel_neon_begin();
+			pmull_gcm_encrypt_block(iv, iv, ctx->aes_key.key_enc,
 						num_rounds(&ctx->aes_key));
+			kernel_neon_end();
+		}
+
 	} else {
 		__aes_arm64_encrypt(ctx->aes_key.key_enc, tag, iv,
 				    num_rounds(&ctx->aes_key));