xfs: get rid of count from xfs_iomap_write_allocate()

Get rid of function variable count from xfs_iomap_write_allocate() as
it is unused.

Additionally, checkpatch warn me of the following for this change:
WARNING: extern prototypes should be avoided in .h files
+extern int xfs_iomap_write_allocate(struct xfs_inode *, xfs_off_t,

So this patch also remove all extern function prototypes at xfs_iomap.h
to suppress it to make this code style in consistent manner in this file.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

fs/xfs/xfs_aops.c

@@ -333,7 +333,7 @@ xfs_map_blocks(
 
 	if (type == XFS_IO_DELALLOC &&
 	    (!nimaps || isnullstartblock(imap->br_startblock))) {
-		error = xfs_iomap_write_allocate(ip, offset, count, imap);
+		error = xfs_iomap_write_allocate(ip, offset, imap);
 		if (!error)
 			trace_xfs_map_blocks_alloc(ip, offset, count, type, imap);
 		return -XFS_ERROR(error);

fs/xfs/xfs_iomap.c

@@ -655,7 +655,6 @@ int
 xfs_iomap_write_allocate(
 	xfs_inode_t	*ip,
 	xfs_off_t	offset,
-	size_t		count,
 	xfs_bmbt_irec_t *imap)
 {
 	xfs_mount_t	*mp = ip->i_mount;

fs/xfs/xfs_iomap.h

@@ -21,12 +21,12 @@
 struct xfs_inode;
 struct xfs_bmbt_irec;
 
-extern int xfs_iomap_write_direct(struct xfs_inode *, xfs_off_t, size_t,
+int xfs_iomap_write_direct(struct xfs_inode *, xfs_off_t, size_t,
 			struct xfs_bmbt_irec *, int);
-extern int xfs_iomap_write_delay(struct xfs_inode *, xfs_off_t, size_t,
+int xfs_iomap_write_delay(struct xfs_inode *, xfs_off_t, size_t,
 			struct xfs_bmbt_irec *);
-extern int xfs_iomap_write_allocate(struct xfs_inode *, xfs_off_t, size_t,
+int xfs_iomap_write_allocate(struct xfs_inode *, xfs_off_t,
 			struct xfs_bmbt_irec *);
-extern int xfs_iomap_write_unwritten(struct xfs_inode *, xfs_off_t, size_t);
+int xfs_iomap_write_unwritten(struct xfs_inode *, xfs_off_t, size_t);
 
 #endif /* __XFS_IOMAP_H__*/