boards: arm: nrf9160_pca10090: increase reset line wait time

The 1ms wait time has been shown to not be enough. Increasing to 10ms.

This change has been shown to be necessary after
CONFIG_SYS_CLOCK_TICKS_PER_SEC was changed from 128 to 32768
in https://github.com/zephyrproject-rtos/zephyr/pull/16782



Signed-off-by: Sigurd Olav Nevstad <sigurdolav.nevstad@nordicsemi.no>