evm: Use defined constant for UUID representation

Instead of sizeof use pre-defined constant for UUID representation.

While here, drop the implementation details of uuid_t type.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

security/integrity/evm/evm_crypto.c

@@ -173,8 +173,7 @@ static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
 	crypto_shash_update(desc, (const u8 *)&hmac_misc, sizeof(hmac_misc));
 	if ((evm_hmac_attrs & EVM_ATTR_FSUUID) &&
 	    type != EVM_XATTR_PORTABLE_DIGSIG)
-		crypto_shash_update(desc, &inode->i_sb->s_uuid.b[0],
-				    sizeof(inode->i_sb->s_uuid));
+		crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid, UUID_SIZE);
 	crypto_shash_final(desc, digest);
 }