ARM64: dts: meson-gxbb: adjust nanopi-k2 gpio-line-names

GPIOX22 is now declared properly and TEST_N has been moved so
the gpio-line-names of the nanopi-k2 must be adjusted accordingly

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>