regulator: tps65132: add low power mode control for enable pins

Add ti,en-gpio-lpm property to set the enable pins to input/pull
down state when the boost regulator being disabled. This can reduce the
rock bottom power numbers when system entering into sleep state with the
regulators disabled.

Take this chance to correct a typo of drive-strength property specified
in tps65132-en-pin pin group node for msm8916 QRD SKUH board.

Change-Id: I2c2df1f4893c31deeba02c3b2988d1157bdb7b61
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>