bcachefs: remove redundant assignment to variable ret

Variable ret is being assigned a value that is never read, it is
being re-assigned a couple of statements later on. The assignment
is redundant and can be removed.

Cleans up clang scan build warning:
fs/bcachefs/super-io.c:806:2: warning: Value stored to 'ret' is
never read [deadcode.DeadStores]
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/super-io.c

@@ -804,7 +804,6 @@ static int __bch2_read_super(const char *path, struct bch_opts *opts,
 		goto err;
 	}
 
-	ret = 0;
 	sb->have_layout = true;
 
 	ret = bch2_sb_validate(sb, &err, READ);