pwm: meson: Fix confusing indentation

Fix indentation of return block.  Smatch warning:
    drivers/pwm/pwm-meson.c:139 meson_pwm_request() warn: inconsistent indenting

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Fixes: 211ed630 ("pwm: Add support for Meson PWM Controller")
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>