power: smb135x-charger: fix irq storm

It is observed that when DCIN path is suspend, the read from irq status
registers do not clear the interrupts. This causes an interrupt storm.

The workaround for this issue is to unsuspend DCIN while the interrupt
status registers are read and put back the DCIN in suspend mode if it
were suspended.

Change-Id: Iebe579da62225fcd64c1a88c1292be60ab60f274
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>