iomap: remove superflous pagefault_disable from iomap_write_actor

iov_iter_copy_from_user_atomic disables page faults internally, no need to
do it around the call.  This also brings the iomap code in line with
the original filemap version.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/iomap.c

@@ -194,9 +194,7 @@ iomap_write_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
 		if (mapping_writably_mapped(inode->i_mapping))
 			flush_dcache_page(page);
 
-		pagefault_disable();
 		copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
-		pagefault_enable();
 
 		flush_dcache_page(page);