Remove unused linux/fs.h includes

Prep for fixing conflicts introduced by newer glibc.
cc https://github.com/ostreedev/ostree/issues/2685

src/libostree/ostree-repo-commit.c

@@ -30,7 +30,6 @@
 #include <sys/xattr.h>
 #include <glib/gprintf.h>
 #include <sys/ioctl.h>
-#include <linux/fs.h>
 #include <ext2fs/ext2_fs.h>
 
 #include "otutil.h"

src/ostree/ot-main.c

@@ -28,7 +28,6 @@
 #include <string.h>
 #include <sys/statvfs.h>
 #include <sys/mount.h>
-#include <linux/fs.h>
 
 #include "ot-main.h"
 #include "ostree.h"