xfs: fix xfs_mode_to_ftype() prototype

A harmless warning just got introduced:

fs/xfs/libxfs/xfs_dir2.h:40:8: error: type qualifiers ignored on function return type [-Werror=ignored-qualifiers]

Removing the 'const' modifier avoids the warning and has no
other effect.

Fixes: 1fc4d33 ("xfs: replace xfs_mode_to_ftype table with switch statement")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/libxfs/xfs_dir2.c

@@ -38,7 +38,7 @@ struct xfs_name xfs_name_dotdot = { (unsigned char *)"..", 2, XFS_DIR3_FT_DIR };
 /*
  * Convert inode mode to directory entry filetype
  */
-const unsigned char xfs_mode_to_ftype(int mode)
+unsigned char xfs_mode_to_ftype(int mode)
 {
 	switch (mode & S_IFMT) {
 	case S_IFREG:

fs/xfs/libxfs/xfs_dir2.h

@@ -37,7 +37,7 @@ extern struct xfs_name	xfs_name_dotdot;
 /*
  * Convert inode mode to directory entry filetype
  */
-extern const unsigned char xfs_mode_to_ftype(int mode);
+extern unsigned char xfs_mode_to_ftype(int mode);
 
 /*
  * directory operations vector for encode/decode routines