gpiolib: fix performance regression when using gpio_chip_get_multiple()

gpiolib: fix performance regression when using gpio_chip_get_multiple()

commit 74abd086d2ee ("gpiolib: sanitize the return value of
gpio_chip::get_multiple()") altered the value returned by
gc->get_multiple() in case it is positive (> 0), but failed to return
for other cases (<= 0).

This may result in the "if (gc->get)" block being executed and thus
negates the performance gain that is normally obtained by using
gc->get_multiple().

Fix by returning the result of gc->get_multiple() if it is <= 0.

Also move the "ret" variable to the scope where it is used, which as an
added bonus fixes an indentation error introduced by the aforementioned
commit.

Fixes: 74abd086d2ee ("gpiolib: sanitize the return value of gpio_chip::get_multiple()")
Cc: stable@vger.kernel.org
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20250703191829.2952986-1-hugo@hugovil.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>