This driver doesn't call any DT functions like of_get_property(). Remove
the of.h include as it isn't used.

Cc: Girish Mahadevan <girishm@codeaurora.org>
Cc: Dilip Kota <dkota@codeaurora.org>
Cc: Alok Chauhan <alokc@codeaurora.org>
Cc: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200204191206.97036-4-swboyd@chromium.orgSigned-off-by: Mark Brown <broonie@kernel.org>