tests: device: tweak test to test linker sorting
tests: device: tweak test to test linker sorting

There was a linker script change the broke the sorting such that
priority 2 and 20 would not necessary get sorted correctly.  Modify
the test to try and catch any such issues in the future.

We modify the DEVICE_DEFINE of the larger priority first, so if the
linker isn't sorting it would get linked first in theory, and we also
tweak the priority value from 4 to 20 so if we aren't sorting correctly
between 2 and 20 we'll catch that.

Signed-off-by: Kumar Gala <a5e5248af4cd4f0ed8c515f61d40a6e2db46a66e@linaro.org>

finikorg/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,Vudentz/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,nashif/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,Vudentz/zephyr,galak/zephyr,Vudentz/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,finikorg/zephyr,Vudentz/zephyr,Vudentz/zephyr,nashif/zephyr