serial: msm-geni: remove redundant includes

For whatever reason, likely a driver stub was copied from another
driver, the driver contains a bunch of unnecessary and confusing
includes like watchdog.h etc., the change reduces the list.

Signed-off-by: Vladimir Zapolskiy <vladimir.zapolskiy@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>