mx31pdk: Add MC13783 PMIC support

Add MC13783 PMIC support.

Tested by using the 'date' command, which reads the MC13783 RTC registers:

MX31PDK U-Boot > date
Date: 1970-01-01 (Thursday)    Time:  2:22:35

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>

board/freescale/mx31pdk/mx31pdk.c

@@ -30,6 +30,8 @@
 #include <asm/arch/imx-regs.h>
 #include <asm/arch/sys_proto.h>
 #include <watchdog.h>
+#include <pmic.h>
+#include <fsl_pmic.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -79,6 +81,16 @@ int board_init(void)
 
 int board_late_init(void)
 {
+	u32 val;
+	struct pmic *p;
+
+	pmic_init();
+	p = get_pmic();
+
+	/* Enable RTC battery */
+	pmic_reg_read(p, REG_POWER_CTL0, &val);
+	pmic_reg_write(p, REG_POWER_CTL0, val | COINCHEN);
+	pmic_reg_write(p, REG_INT_STATUS1, RTCRSTI);
 #ifdef CONFIG_HW_WATCHDOG
 	mxc_hw_watchdog_enable();
 #endif