mmc: core: Add DT bindings for eMMC hardware reset support

Sometime only need set MMC_CAP_HW_RESET for one of MMC hosts,
So set it in device tree is better.

Signed-off-by: Chaotian Jing <chaotian.jing@mediatek.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/mmc.txt

@@ -37,6 +37,7 @@ Optional properties:
 - sd-uhs-sdr104: SD UHS SDR104 speed is supported
 - sd-uhs-ddr50: SD UHS DDR50 speed is supported
 - cap-power-off-card: powering off the card is safe
+- cap-mmc-hw-reset: eMMC hardware reset is supported
 - cap-sdio-irq: enable SDIO IRQ signalling on this interface
 - full-pwr-cycle: full power cycle of the card is supported
 - mmc-ddr-1_8v: eMMC high-speed DDR mode(1.8V I/O) is supported

drivers/mmc/core/host.c

@@ -267,6 +267,8 @@ int mmc_of_parse(struct mmc_host *host)
 		host->caps |= MMC_CAP_UHS_DDR50;
 	if (of_property_read_bool(np, "cap-power-off-card"))
 		host->caps |= MMC_CAP_POWER_OFF_CARD;
+	if (of_property_read_bool(np, "cap-mmc-hw-reset"))
+		host->caps |= MMC_CAP_HW_RESET;
 	if (of_property_read_bool(np, "cap-sdio-irq"))
 		host->caps |= MMC_CAP_SDIO_IRQ;
 	if (of_property_read_bool(np, "full-pwr-cycle"))