witherspoon: Only rebind ucd9000 if we unbound it

This makes way for an incoming kernel patch affecting Witherspoon[1],
where we disable the UCD90160 device in the devicetree. If the driver
hasn't been bound to the device we can immediately proceed to invoking
i2c{g,s}et. Finally if it wasn't bound before the script was executed
then don't try to rebind it, as it was disabled for a reason

[1] https://lists.ozlabs.org/pipermail/openbmc/2017-March/007015.html

Change-Id: Icc1fd1aa978e1a5cd62f1609bae97aa7dbfcde41
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
1 file changed