fs/squashfs: squashfs.h: include file should be self dependent

Otherwise, we get a lot of errors when including this file.

Signed-off-by: Richard Genoud <richard.genoud@bootlin.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: João Marcos Costa <joaomarcos.costa@bootlin.com>

include/squashfs.h

@@ -10,7 +10,10 @@
 #ifndef _SQFS_H_
 #define _SQFS_H_
 
-struct disk_partition;
+#include <fs.h>
+#include <blk.h>
+#include <part.h>
+#include <linux/types.h>
 
 int sqfs_opendir(const char *filename, struct fs_dir_stream **dirsp);
 int sqfs_readdir(struct fs_dir_stream *dirs, struct fs_dirent **dentp);