Needed for PWM control suuported by the PMIC

CC: Samuel Ortiz <sameo@linux.intel.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Acked-by: NLee Jones <lee.jones@linaro.org>
Tested-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NShobhit Kumar <shobhit.kumar@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>