boards: riscv: rv32m1_vega: remove no power-save limitation
boards: riscv: rv32m1_vega: remove no power-save limitation

Now the VEGABoard BLE supports power-saving,
so the docs need to be updated accordingly.

Signed-off-by: George Stefan <11b7ded0869ce13e68fb921c45ab79f0dd65a672@nxp.com>

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