[GFS2] Spelling sentinal -> sentinel

A spelling mistake (one of mine).

Cc: Jan Engelhardt <jengelh@linux01.gwdg.de>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/ops_file.c b/fs/gfs2/ops_file.c
index f5ddd49..9dcf72a 100644
--- a/fs/gfs2/ops_file.c
+++ b/fs/gfs2/ops_file.c
@@ -79,7 +79,7 @@
  * any other part of this. Its use is purely as a flag so that we
  * know (in readpage()) whether or not do to locking.
  */
-struct file gfs2_internal_file_sentinal = {
+struct file gfs2_internal_file_sentinel = {
 	.f_flags = O_NOATIME|O_RDONLY,
 };
 
@@ -112,7 +112,7 @@
 	desc.count = size;
 	desc.error = 0;
 	do_generic_mapping_read(inode->i_mapping, ra_state,
-				&gfs2_internal_file_sentinal, pos, &desc,
+				&gfs2_internal_file_sentinel, pos, &desc,
 				gfs2_read_actor);
 	return desc.written ? desc.written : desc.error;
 }