mfd: Add support for twl6041

The delta between twl6040 and twl6041 is small, the main difference is in
the number of GPOs (3 on twl6040, 1 on twl6041).

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>