mmc: sdhci-omap: Set caps2 to indicate no physical write protect pin

After commit 6d5cd068ee ("mmc: sdhci: use WP GPIO in
sdhci_check_ro()") and commit 39ee32ce48 ("mmc: sdhci-omap: drop
->get_ro() implementation"), sdhci-omap relied on SDHCI_PRESENT_STATE
to check if the card is read-only, if wp-gpios is not populated
in device tree. However SDHCI_PRESENT_STATE in sdhci-omap does not have
correct read-only state.

sdhci-omap can be used by platforms with both micro SD slot and standard
SD slot with physical write protect pin (using GPIO). Set caps2 to
MMC_CAP2_NO_WRITE_PROTECT based on if wp-gpios property is populated or
not.

This fix is required since existing device-tree node doesn't have
"disable-wp" property and to preserve old-dt compatibility.

Fixes: 6d5cd068ee ("mmc: sdhci: use WP GPIO in sdhci_check_ro()")
Fixes: 39ee32ce48 ("mmc: sdhci-omap: drop ->get_ro() implementation")
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-omap.c

@@ -1056,6 +1056,9 @@ static int sdhci_omap_probe(struct platform_device *pdev)
 			mmc->f_max = 48000000;
 	}
 
+	if (!mmc_can_gpio_ro(mmc))
+		mmc->caps2 |= MMC_CAP2_NO_WRITE_PROTECT;
+
 	pltfm_host->clk = devm_clk_get(dev, "fck");
 	if (IS_ERR(pltfm_host->clk)) {
 		ret = PTR_ERR(pltfm_host->clk);