power: smb1360: shutdown smb1360 when device suspend or powered off

The fuel gauge in smb1360 is active whenever system is in sleep or
powered off. It does ADC sampling every 1.5 seconds, increasing the
standby current by about 100uA. This current number may cause concerns
on power numbers when device powered off or suspend.

Add an optional property "qcom,disable-fg-after-pwroff" to shutdown
smb1360 when device is powered off. Add an optional property
"qcom,disable-fg-in-sleep" to shutdown smb1360 when application
processor subsystem (APSS) going to suspend, and power on it when APSS
resumes. Doing this achives us 100uA in sleep, however as there is no
fuel gauge sampling during sleep there may be a loss of SOC accuracy.

After forcing smb1360 to shutdown when system suspends, smb1360 cannot
generate any wakeup interrupt to notify low system SoC or low battery
voltage. To make sure that the system does a graceful shutdown as low
SOC, use the PMIC adc BTM for a low voltage wakeup notification.

Change-Id: I9461e295dfd0ec6d1154068d88b7e3f1b45afb4f
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>