mfd: rtsx: Implement driving adjustment to device-dependent callbacks

Implement different ways of selecting driving capability(a necessary adjustment
along with voltage change). It was origionally in device-independent
mmc/host/rtsx_pci_sdmmc.c. Moving it here to support devices which may have a
different way of adjustment.

Signed-off-by: Roger Tseng <rogerable@realtek.com>
Reviewed-by: Wei WANG <wei_wang@realsil.com.cn>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/rts5229.c b/drivers/mfd/rts5229.c
index 29d889c..58af4db 100644
--- a/drivers/mfd/rts5229.c
+++ b/drivers/mfd/rts5229.c
@@ -119,10 +119,18 @@
 	int err;
 
 	if (voltage == OUTPUT_3V3) {
+		err = rtsx_pci_write_register(pcr,
+				SD30_DRIVE_SEL, 0x07, DRIVER_TYPE_D);
+		if (err < 0)
+			return err;
 		err = rtsx_pci_write_phy_register(pcr, 0x08, 0x4FC0 | 0x24);
 		if (err < 0)
 			return err;
 	} else if (voltage == OUTPUT_1V8) {
+		err = rtsx_pci_write_register(pcr,
+				SD30_DRIVE_SEL, 0x07, DRIVER_TYPE_B);
+		if (err < 0)
+			return err;
 		err = rtsx_pci_write_phy_register(pcr, 0x08, 0x4C40 | 0x24);
 		if (err < 0)
 			return err;