pcie: designware: mvebu: fix reset release polarity

The dm_gpio_set_value() routine sets signal logical level, with
GPIO_ACTIVE_LOW/HIGH value taken into account. Reset active value is 1
(asserted), while reset inactive value is 0 (de-asserted). Fix the reset
toggle code to set the correct reset logic value.

Reported-by: Sven Auhagen <sven.auhagen@voleatech.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Stefan Roese <sr@denx.de>