hikey: Disable VBUS_DET interrupt for PMIC

After disconnect Jumper pin 1-2 in J15 header, the signal VBUS_DET is to
be pulled down to low level. This will assert the interrupt signal in
PMIC and trigger IRQ in GIC; the asserted signal from VBUS_DET is level
triggered and kernel reports the warning for unhooked interrupt handling;
and VBUS_DET stays with low level, this triggers IRQ storm in kernel.

This patch is to disable interrupt for VBUS_DET in PMIC, this can
dismiss the verbose log and IRQ storm after kernel booting.

[   40.835279] irq 57: nobody cared (try booting with the "irqpoll" option)
[   40.842075] CPU: 0 PID: 980 Comm: irq/57-hi655x-p Not tainted 4.4.77-568944-g576a0114dec8-dirty #667
[   40.851303] Hardware name: HiKey Development Board (DT)
[   40.856580] Call trace:
[   40.859060] [<ffffff800808c4cc>] dump_backtrace+0x0/0x1e0
[   40.864516] [<ffffff800808c8ac>] show_stack+0x20/0x28
[   40.869622] [<ffffff80084b9688>] dump_stack+0xa8/0xe0
[   40.874729] [<ffffff800812dd5c>] __report_bad_...

plat/hisilicon/hikey/hikey_bl1_setup.c

@@ -288,6 +288,11 @@ static void hikey_hi6553_init(void)
 
 	/* select 32.764KHz */
 	mmio_write_8(HI6553_CLK19M2_600_586_EN, 0x01);
+
+	/* Disable vbus_det interrupts */
+	data = mmio_read_8(HI6553_IRQ2_MASK);
+	data = data | 0x3;
+	mmio_write_8(HI6553_IRQ2_MASK, data);
 }
 
 static void init_mmc0_pll(void)

plat/hisilicon/hikey/include/hi6553.h

@@ -19,6 +19,7 @@
 #define DISABLE6_XO_CLK_RF2			(1 << 4)
 
 #define HI6553_VERSION_REG			(PMUSSI_BASE + (0x000 << 2))
+#define HI6553_IRQ2_MASK			(PMUSSI_BASE + (0x008 << 2))
 #define HI6553_ENABLE2_LDO1_8			(PMUSSI_BASE + (0x029 << 2))
 #define HI6553_DISABLE2_LDO1_8			(PMUSSI_BASE + (0x02a << 2))
 #define HI6553_ONOFF_STATUS2_LDO1_8		(PMUSSI_BASE + (0x02b << 2))