nfsd: fix fall-through annotations

Replace "fallthru" with a proper "fall through" annotation.

Also, add an annotation were it is expected to fall through.

These fixes are part of the ongoing efforts to enabling
-Wimplicit-fallthrough

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/vfs.c

@@ -1406,6 +1406,7 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 					*created = 1;
 				break;
 			}
+			/* fall through */
 		case NFS4_CREATE_EXCLUSIVE4_1:
 			if (   d_inode(dchild)->i_mtime.tv_sec == v_mtime
 			    && d_inode(dchild)->i_atime.tv_sec == v_atime
@@ -1414,7 +1415,7 @@ do_nfsd_create(struct svc_rqst *rqstp, struct svc_fh *fhp,
 					*created = 1;
 				goto set_attr;
 			}
-			 /* fallthru */
+			/* fall through */
 		case NFS3_CREATE_GUARDED:
 			err = nfserr_exist;
 		}