board: venice: add FSA support

board: venice: add FSA support

The Gateworks Flexible Socket Adapters adapt common
busses such as SDIO/UART/USB/PCI to various connectors
such as M.2 B-Key, M.2 E-Key, M.2 M-Key, and MiniPCIe.

Each FSA has an EEPROM onboard describing its details as well as an
optional port-expander for configurable GPIO's.

Add support for identifying the FSA's and configuring their
details such as user description and GPIO's:
 - enable pca953x, pca954x and eeprom support for communicating
   with the I2C eeprom and gpio port expander on the FSA
 - add FSA detection support
 - add FSA gpio configuration support

Each FSA is identified in the device-tree by an alias to it's I2C
bus where an eeprom@54 node must exist as well as an gpio@20 node
for an io-expander. These nodes must be enabled so that
they can be probed to determine if they are actually present in
the system. If not present or not enabled the gpio expander can
not be used. This also requires livetree as the gpio expander
node if not present must be disabled.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>