mtd: Stop assuming mtd_erase() is asynchronous

None of the mtd->_erase() implementations work in an asynchronous manner,
so let's simplify MTD users that call mtd_erase(). All they need to do
is check the value returned by mtd_erase() and assume that != 0 means
failure.

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Richard Weinberger <richard@nod.at>

drivers/mtd/devices/bcm47xxsflash.c

@@ -95,9 +95,6 @@ static int bcm47xxsflash_erase(struct mtd_info *mtd, struct erase_info *erase)
 	else
 		erase->state = MTD_ERASE_DONE;
 
-	if (erase->callback)
-		erase->callback(erase);
-
 	return err;
 }