boards: arm: cc1352*/cc26x2r1: add mcuboot-{led0,button0} aliases

This adds DT aliases for LED and button used in recovery mode of the
MCUboot bootloader, on the following CC13x2/CC26x2 based boards:

- CC1352P1 LaunchXL (CC1352P)
- CC1352R1 LaunchXL (CC1352R)
- CC1352R SensorTag (CC1352R)
- CC26x2R1 LaunchXL (CC2652R)

For all boards a red LED and second button (not the one used by the
TI ROM bootloader) was selected.

Signed-off-by: Piotr Dymacz <pepe2k@gmail.com>