fs/cramfs/inode.c: initialize file_ra_state

file_ra_state_init() assumes that the file_ra_state has been zeroed out. 
Fixes a KMSAN used-unintialized issue (at least).

Fixes: cf948cb ("cramfs: read_mapping_page() is synchronous")
Reported-by: syzbot <syzbot+8ce7f8308d91e6b8bbe2@syzkaller.appspotmail.com>
  Link: https://lkml.kernel.org/r/0000000000008f74e905f56df987@google.com
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/cramfs/inode.c

@@ -183,7 +183,7 @@ static void *cramfs_blkdev_read(struct super_block *sb, unsigned int offset,
 				unsigned int len)
 {
 	struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
-	struct file_ra_state ra;
+	struct file_ra_state ra = {};
 	struct page *pages[BLKS_PER_BUF];
 	unsigned i, blocknr, buffer;
 	unsigned long devsize;