rename hvpmic -> max17135

The `hvpmic' module really is only about the Maxim MAX17135,
so it is now renamed to max17135 to allow other HVPMIC chips
to be implemented.

+ minor code tweaks
add support for TI TPS65185 HVPMIC

Add API with Doxygen and implementation to set the power up/down
sequences, VCOM register value, control each power rail,
enable/disable the HV outputs and wait for the transitions to
complete.
Android.mk: update with max17135 and tps65185
max17135: fix compiler warning about unused variable
ChangeLog v1.1 -> v1.2