power: smb135x-charger: stay awake during i2c transactions

I2C transactions can timeout if the bus is already suspended when the
I2C transaction is initiated. Prevent this by holding the device awake
during I2C transactions.

Note that if the transaction is initiated after suspend_noirq, the
transaction will still timeout, but the I2C retry will ensure the
transction goes through.

CRs-Fixed: 878738
Change-Id: I780a7ddfc7a25f9796dbe19a16c15cee66a2e0ed
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>