mmc: atmel_sdhci: re-enable sdhci after SD Card re-insertion

Whenever the SD Card would be removed and then re-inserted while in the
U-Boot command line, the `SDBPWR` bit of the `SDMMC_PCR` register would
remain unset afterwards. In order for the bit to be set again after
re-insertion, register an additional `deferred_probe` method that the
DM would then transparently call. This method will call the generic
`sdhci_probe` which will, during its execution flow, set this bit to 1.

Signed-off-by: Sergiu Moga <sergiu.moga@microchip.com>
Reported-by: Mihai Sain <mihai.sain@microchip.com>
Reviewed-by: Eugen Hristev <eugen.hristev@microchip.com>
diff --git a/drivers/mmc/atmel_sdhci.c b/drivers/mmc/atmel_sdhci.c
index 2b5ceea..37b0bee 100644
--- a/drivers/mmc/atmel_sdhci.c
+++ b/drivers/mmc/atmel_sdhci.c
@@ -52,6 +52,17 @@
 	struct mmc mmc;
 };
 
+static int atmel_sdhci_deferred_probe(struct sdhci_host *host)
+{
+	struct udevice *dev = host->mmc->dev;
+
+	return sdhci_probe(dev);
+}
+
+static const struct sdhci_ops atmel_sdhci_ops = {
+	.deferred_probe	= atmel_sdhci_deferred_probe,
+};
+
 static int atmel_sdhci_probe(struct udevice *dev)
 {
 	struct mmc_uclass_priv *upriv = dev_get_uclass_priv(dev);
@@ -104,6 +115,7 @@
 		return ret;
 
 	host->mmc->priv = host;
+	host->ops = &atmel_sdhci_ops;
 	upriv->mmc = host->mmc;
 
 	clk_free(&clk);