staging: lustre: missed a few cases of using NULL instead of 0

It is preferable to use NULL instead of 0 for pointers. This fixes sparse
warnings such as:

lustre/fld/fld_request.c:126:17: warning: Using plain integer as NULL pointer

The second parameter of class_match_param() was changed to a const, to
be able to remove a cast in one user, to prevent splitting a long
line. No other code change.
Signed-off-by: Frank Zago <fzago@cray.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5396
Reviewed-on: http://review.whamcloud.com/12567Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lnet/lnet/api-ni.c

@@ -904,7 +904,7 @@ lnet_ping_info_setup(lnet_ping_info_t **ppinfo, lnet_handle_md_t *md_handle,
 {
 	lnet_process_id_t id = {LNET_NID_ANY, LNET_PID_ANY};
 	lnet_handle_me_t me_handle;
-	lnet_md_t md = {0};
+	lnet_md_t md = { NULL };
 	int rc, rc2;
 
 	if (set_eq) {

drivers/staging/lustre/lustre/llite/llite_lib.c

@@ -1940,7 +1940,7 @@ int ll_prep_inode(struct inode **inode, struct ptlrpc_request *req,
 		  struct super_block *sb, struct lookup_intent *it)
 {
 	struct ll_sb_info *sbi = NULL;
-	struct lustre_md md;
+	struct lustre_md md = { NULL };
 	int rc;
 
 	LASSERT(*inode || sb);

drivers/staging/lustre/lustre/obdclass/obd_config.c

@@ -72,7 +72,7 @@ EXPORT_SYMBOL(class_find_param);
 
 /* returns 0 if this is the first key in the buffer, else 1.
    valp points to first char after key. */
-static int class_match_param(char *buf, char *key, char **valp)
+static int class_match_param(char *buf, const char *key, char **valp)
 {
 	if (!buf)
 		return 1;
@@ -1008,7 +1008,7 @@ int class_process_proc_param(char *prefix, struct lprocfs_vars *lvars,
 		/* Search proc entries */
 		while (lvars[j].name) {
 			var = &lvars[j];
-			if (class_match_param(key, (char *)var->name, NULL) == 0
+			if (!class_match_param(key, var->name, NULL)
 			    && keylen == strlen(var->name)) {
 				matched++;
 				rc = -EROFS;