power: pm8921-charger: remove efficiency improvements

Writing 0x8C to 0x209 makes the pmic charging efficient but causes
a voltage to appear on usb after it is removed. This makes the
phone never detect usb removal.  Remove writing 0x8C to 0x209.

Also remove writing 0xF1 to 0x209. This was thought to be helping
with the issue, but it did not help.

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