pstore: use mount option instead sysfs to tweak kmsg_bytes

/sys/fs is a somewhat strange way to tweak what could more
obviously be tuned with a mount option.

Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/pstore/internal.h b/fs/pstore/internal.h
index 76c26d2..8c9f23e 100644
--- a/fs/pstore/internal.h
+++ b/fs/pstore/internal.h
@@ -1,7 +1,6 @@
+extern void	pstore_set_kmsg_bytes(int);
 extern void	pstore_get_records(void);
 extern int	pstore_mkfile(enum pstore_type_id, char *psname, u64 id,
 			      char *data, size_t size,
 			      struct timespec time, int (*erase)(u64));
 extern int	pstore_is_mounted(void);
-
-extern struct kobj_attribute pstore_kmsg_bytes_attr;