mmc: sdhci_pltfm: Constify sdhci_pltfm_data

The sdhci_pltfm_data struct is never modified within the sdhci_pltfm
module. So make the pdata parameter to sdhci_pltfm_init and
sdhci_pltfm_register const.  This allows drivers to declare their
sdhci_pltfm_data struct as const.

This patch also makes the sdhci_pltfm_data declarations const where
possible.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index 78ac002..68c301d 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -412,7 +412,7 @@
 	.platform_bus_width = esdhc_pltfm_bus_width,
 };
 
-static struct sdhci_pltfm_data sdhci_esdhc_imx_pdata = {
+static const struct sdhci_pltfm_data sdhci_esdhc_imx_pdata = {
 	.quirks = ESDHC_DEFAULT_QUIRKS | SDHCI_QUIRK_NO_HISPD_BIT
 			| SDHCI_QUIRK_NO_ENDATTR_IN_NOPDESC
 			| SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC