affects all hiby targets, fiiom3k, and ibasso dx50/dx90
As well as deduplicating a small pile of code, this also implements
hysteresis so we're not doing a sysfs read/lookup multiple times
back-to-back every time the power management tick fires.
Change-Id: I2f7672acbb36341becf67e07960c24c681270d09
* Cannot turn off the LCD directly (have to rely on backlight)
* Only insmod/rmmod the usb gadget modules if state changes
Change-Id: I9ea90177d496cd035ada93e04a93a7c6f2e84706
Most credit goes to: Roman Skylarov
Additional integration and refactoring by myself.
*** COMPLETELY UNTESTED ***
Change-Id: Ia64c36d92e0214c6b15f7a868df286f8113ea27b
