mfd: rtsx: Add shutdown callback in rtsx_pci_driver

Some actions to clear power state should be handled in .shutdown
callback in rtsx_pci_driver. This patch adopts the following measures to
catch this goal:
1. Add a function rtsx_pci_power_off to abstract the common ops in
.shutdown and .suspend
2. Add pcr->ops->force_power_down to fulfill the individual action for
each reader model

Signed-off-by: Wei WANG <wei_wang@realsil.com.cn>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/mfd/rts5209.c b/drivers/mfd/rts5209.c
index 2170449..c67935e 100644
--- a/drivers/mfd/rts5209.c
+++ b/drivers/mfd/rts5209.c
@@ -59,6 +59,11 @@
 	}
 }
 
+static void rts5209_force_power_down(struct rtsx_pcr *pcr)
+{
+	rtsx_pci_write_register(pcr, FPDCTL, 0x07, 0x07);
+}
+
 static int rts5209_extra_init_hw(struct rtsx_pcr *pcr)
 {
 	rtsx_pci_init_cmd(pcr);
@@ -197,6 +202,7 @@
 	.switch_output_voltage = rts5209_switch_output_voltage,
 	.cd_deglitch = NULL,
 	.conv_clk_and_div_n = NULL,
+	.force_power_down = rts5209_force_power_down,
 };
 
 /* SD Pull Control Enable: