smc911x: split out useful defines/functions into local header

smc911x: split out useful defines/functions into local header

The smc911x driver has a lot of useful defines/functions which can be used
by pieces of code (such as example eeprom programmers).  Rather than
forcing each place to duplicate these defines/functions, split them out
of the smdc911x driver into a local header.

Signed-off-by: Mike Frysinger <[email protected]>
Acked-by: Ben Warren <[email protected]>
CC: Sascha Hauer <[email protected]>
CC: Guennadi Liakhovetski <[email protected]>
CC: Magnus Lilja <[email protected]>
CC: Ben Warren <[email protected]>