block: fix rootwait=

Failures to look up the gendisk must return -ENODEV so that rootwait
retries the lookup instead of -EINVAL which exits early.

Fixes: cf056a431215 ("init: improve the name_to_dev_t interface")
Reported-by: Fabio Estevam <[e-mail]>
Signed-off-by: Christoph Hellwig <[e-mail]>
Tested-by: Fabio Estevam <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jens Axboe <[e-mail]>

block/early-lookup.c

···
 	*p = '\0';
 	*devt = blk_lookup_devt(s, part);
 	if (*devt)
-		return 0;
+		return -ENODEV;
 
 	/* try disk name without p<part number> */
 	if (p < s + 2 || !isdigit(p[-2]) || p[-1] != 'p')
···
 	*devt = blk_lookup_devt(s, part);
 	if (*devt)
 		return 0;
-	return -EINVAL;
+	return -ENODEV;
 }
 
 static int __init devt_from_devnum(const char *name, dev_t *devt)