[asus-port] [RFC] PXA27x core voltage change sequencer

Hi all,

It seems like we already have 3 devices which have MAX158xx PMICs:
a730, hx4700 and some HTC one. I think it's time to unify things.
Patch with mach-unspecific driver attached. Tested on hx4700.

I'm asking for comments and suggestions, especially about files
names and placement. :-)

And...

Michal, I see that a730 not using sequencer, but fully capable I2C
controller. Is it mandatory for the a730, or you've just using it
because it's a bit faster (for sending one byte :-). If it's really
mandatory for the a730, then we should write three another drivers:

 - drivers/i2c/busses/i2c-pwr-pxa.c (using drivers/i2c/busses/i2c-pxa.c
   as reference)
 - drivers/i2c/chips/max158xx.c
 - and some glue driver, which using two above plus hooks onto cpufreq
   notifier.

I see no need for doing this if solution with less entropy exists.

Thanks!

-- Anton (irc: bd2)