Data In Polarity and Blink Enable registers are set unconditionally
for all GPIO pins during attach.
It turned out that additional configuration may have side effects
on the output pins, which was observed as a boot hang on
MacchiatoBin and CN913x-DB, whose PCIE slots' reset signals are
connected to the GPIO lines.
Note that it only occurred when booting with FDT (both from
most recent U-Boot or EDK2), whereas ACPI is unaffected since
GPIO kernel driver remains unused with it.
As a fix remove default configuration of GPIO_DATA_IN_POL and
GPIO_BLINK_ENA registers and update them only when
explicity requested - otherwise rely on the firmware settings.