mmc: sdhci-tegra: Add comment for PADCALIB and PAD_CONTROL NVQUIRKS

This patch adds comments about NVQUIRKS HAS_PADCALIB and NEEDS_PAD_CONTROL.
Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Link: https://lore.kernel.org/r/1591326240-28928-1-git-send-email-skomatineni@nvidia.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-tegra.c

@@ -96,7 +96,16 @@
 #define NVQUIRK_ENABLE_SDR50				BIT(3)
 #define NVQUIRK_ENABLE_SDR104				BIT(4)
 #define NVQUIRK_ENABLE_DDR50				BIT(5)
+/*
+ * HAS_PADCALIB NVQUIRK is for SoC's supporting auto calibration of pads
+ * drive strength.
+ */
 #define NVQUIRK_HAS_PADCALIB				BIT(6)
+/*
+ * NEEDS_PAD_CONTROL NVQUIRK is for SoC's having separate 3V3 and 1V8 pads.
+ * 3V3/1V8 pad selection happens through pinctrl state selection depending
+ * on the signaling mode.
+ */
 #define NVQUIRK_NEEDS_PAD_CONTROL			BIT(7)
 #define NVQUIRK_DIS_CARD_CLK_CONFIG_TAP			BIT(8)
 #define NVQUIRK_CQHCI_DCMD_R1B_CMD_TIMING		BIT(9)