mmc: block: add eMMC hardware reset support

For cards that support hardware reset (just eMMC), try a reset and
retry before returning an I/O error.  However this is not done for
ECC errors and is never done twice for the same operation type
(READ, WRITE, DISCARD, SECURE DISCARD) until that type of operation
again succeeds.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/core/core.c

@@ -1529,7 +1529,7 @@ static int mmc_do_erase(struct mmc_card *card, unsigned int from,
 	if (err) {
 		printk(KERN_ERR "mmc_erase: group start error %d, "
 		       "status %#x\n", err, cmd.resp[0]);
-		err = -EINVAL;
+		err = -EIO;
 		goto out;
 	}
 
@@ -1544,7 +1544,7 @@ static int mmc_do_erase(struct mmc_card *card, unsigned int from,
 	if (err) {
 		printk(KERN_ERR "mmc_erase: group end error %d, status %#x\n",
 		       err, cmd.resp[0]);
-		err = -EINVAL;
+		err = -EIO;
 		goto out;
 	}