dm verity: Fix compilation warning

For the case !CONFIG_DM_VERITY_VERIFY_ROOTHASH_SIG, declare the
functions verity_verify_root_hash(), verity_verify_is_sig_opt_arg(),
verity_verify_sig_parse_opt_args() and verity_verify_sig_opts_cleanup()
as inline to avoid a "no previous prototype for xxx" compilation
warning when compiling with W=1.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Author: damien-lemoal

drivers/md/dm-verity-verify-sig.h

@@ -34,25 +34,25 @@ void verity_verify_sig_opts_cleanup(struct dm_verity_sig_opts *sig_opts);
 
 #define DM_VERITY_ROOT_HASH_VERIFICATION_OPTS 0
 
-int verity_verify_root_hash(const void *data, size_t data_len,
-			    const void *sig_data, size_t sig_len)
+static inline int verity_verify_root_hash(const void *data, size_t data_len,
+					  const void *sig_data, size_t sig_len)
 {
 	return 0;
 }
 
-bool verity_verify_is_sig_opt_arg(const char *arg_name)
+static inline bool verity_verify_is_sig_opt_arg(const char *arg_name)
 {
 	return false;
 }
 
-int verity_verify_sig_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
-				    struct dm_verity_sig_opts *sig_opts,
-				    unsigned int *argc, const char *arg_name)
+static inline int verity_verify_sig_parse_opt_args(struct dm_arg_set *as,
+			struct dm_verity *v, struct dm_verity_sig_opts *sig_opts,
+			unsigned int *argc, const char *arg_name)
 {
 	return -EINVAL;
 }
 
-void verity_verify_sig_opts_cleanup(struct dm_verity_sig_opts *sig_opts)
+static inline void verity_verify_sig_opts_cleanup(struct dm_verity_sig_opts *sig_opts)
 {
 }