pinctrl: pic32: Use devm_pinctrl_register() for pinctrl registration

Use devm_pinctrl_register() for pin control registration.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Reviewed-by: Joshua Henderson <joshua.henderson@microchip.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>