The I2C mux control relies on the SDP setting in the ESDP register
so it is necessary to restore the value after a MAC reset.  Combine
all this functionality in to a support function.
Signed-off-by: NDon Skidmore <donald.c.skidmore@intel.com>
Tested-by: NKrishneil Singh <krishneil.k.singh@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>