tegra2: Enable MMC for Seaboard

This adds the required GPIO and pinmux configuration to make eMMC / SD work
on Seaboard.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Tom Warren <twarren@nvidia.com>
diff --git a/drivers/mmc/tegra2_mmc.c b/drivers/mmc/tegra2_mmc.c
index a71785c..9e741f2 100644
--- a/drivers/mmc/tegra2_mmc.c
+++ b/drivers/mmc/tegra2_mmc.c
@@ -452,7 +452,7 @@
 		mmc->host_caps = MMC_MODE_8BIT;
 	else
 		mmc->host_caps = MMC_MODE_4BIT;
-	mmc->host_caps |= MMC_MODE_HS_52MHz | MMC_MODE_HS;
+	mmc->host_caps |= MMC_MODE_HS_52MHz | MMC_MODE_HS | MMC_MODE_HC;
 
 	/*
 	 * min freq is for card identification, and is the highest