When the bootloader starts only IRAM is available, the first task is to
ask the PMU to verify if the iPod has previously been hibernated by OF.
Due to memory limitations, the kernel cannot be used on this stage.
This patch modifies I2C and PMU low level functions to not to depend
on kernel (removes mutexes, and uses HW timer instead of current_tick),
actual kernel functions are modified to be 'mutexed' wrappers of the new
functions.
Change-Id: I7cef9e95dedaf176dc0659315f3dc33166d5b116
469d645390