soc/arm/microchip_mec/mec17x: Initialise GPIO after ECIA

Since bb590b5b, which enforces a more consistent ordering of
initialisation for devices, the ECIA initialisation was happening after
GPIO initialisation. This caused interrupts to stop working on GPIO
input.

This patch fixes that by increasing the default GPIO initialisation
priority, so that it happens after ECIA.

Signed-off-by: Ederson de Souza <ederson.desouza@intel.com>