UCD registers for fault analysis

[Matt Spinler]

Hi Joel,

I opened issue https://github.com/openbmc/openbmc/issues/1727 to 
describe some UCD90160 registers we need to be able to access in order 
to do power fault analysis.   Please take a look and see if its doable 
to add these to a driver.

They are:

* CLEAR_FAULTS - command 0x03
* Clear logged faults - write 0x00 to register 0xEA
* STATUS_WORD - 0x79
* STATUS_VOUT - 0x7A - all pages
* NUM_PAGES - 0xD6 - though maybe we can get the number of pages another way
* MFR_STATUS - 0xF3 - page 0 - for reading the GPI bits

Also:

Write, 0xFA 0x08
Read, 0xFB
Write, 0xFA 0x09
Read, 0xFB
Write, 0xFA 0x0A
Read, 0xFB
Write, 0xFA 0x0E
Read, 0xFB
Write, 0xFA 0x11
Read, 0xFB
Write, 0xFA 0x0B
Read, 0xFB

I also have a document I will send you offline.