lora: sx126x: update modem state on transitions
lora: sx126x: update modem state on transitions

Update the global state of the modem on calls to `SX126xReset` and
`SX126xWakeup`. This stops `SX126xCheckDeviceReady` sending spurious SPI
commands on every transieve before `SX126xSetOperatingMode` is called.

Signed-off-by: Jordan Yates <d74a90e280bbad1cc3646781a4e234b467b60fe1@data61.csiro.au>

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