platform: msm_shared: Add property for io switch

For some platforms the SDC controller is shared between
emmc and sd card. In such case the voltage switch should happen
to 1.8 for emmc card functionality. Add target specific property
to enable the IO_PAD power switch.

Change-Id: Ia5585fff31359f8bd5c7f3b9fb8e909a7e673a90
diff --git a/platform/msm_shared/mmc_sdhci.c b/platform/msm_shared/mmc_sdhci.c
index a31cf87..411f22c 100644
--- a/platform/msm_shared/mmc_sdhci.c
+++ b/platform/msm_shared/mmc_sdhci.c
@@ -1091,6 +1091,7 @@
 	data->pwrctl_base = cfg->pwrctl_base;
 	data->pwr_irq = cfg->pwr_irq;
 	data->slot = cfg->slot;
+	data->use_io_switch = cfg->use_io_switch;
 
 	host->msm_host = data;