mmc: core: Do regular power cycle when lacking eMMC HW reset support

The eMMC HW reset may be implemented either via the host ops ->hw_reset()
callback or through DT and the eMMC pwrseq. Additionally some eMMC cards
don't support HW reset.

To allow a reset to be done for the different combinations of mmc hosts
and eMMC/MMC cards, let's implement a fallback via trying a regular power
cycle. This improves the mmc block layer retry mechanism of failing I/O
requests.

Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
[Ulf: Rewrote changelog]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index f80b3ab..99275e4 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2456,8 +2456,9 @@
 	ret = host->bus_ops->reset(host);
 	mmc_bus_put(host);
 
-	if (ret != -EOPNOTSUPP)
-		pr_warn("%s: tried to reset card\n", mmc_hostname(host));
+	if (ret)
+		pr_warn("%s: tried to reset card, got error %d\n",
+			mmc_hostname(host), ret);
 
 	return ret;
 }