kconfig: BT: Default to using BT_CTLR when BT
kconfig: BT: Default to using BT_CTLR when BT

As reported in issue #9494, BT samples are using the off-chip
UART-based BT controller on 52810. But the on-chip BT controller is
supported on 52810, so this is the reasonable default when BT is
enabled.

This patch enables BT_CTLR by default when BT is enabled.

This resolves #9494.

Signed-off-by: Sebastian Bøe <edee888afd63e94916688495334700803eba20a0@nordicsemi.no>

zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,galak/zephyr,ldts/zephyr,Vudentz/zephyr,finikorg/zephyr,Vudentz/zephyr,finikorg/zephyr,explora26/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,nashif/zephyr,galak/zephyr,punitvara/zephyr,explora26/zephyr,Vudentz/zephyr,ldts/zephyr,finikorg/zephyr,nashif/zephyr,kraj/zephyr,punitvara/zephyr,galak/zephyr,Vudentz/zephyr,ldts/zephyr,Vudentz/zephyr,Vudentz/zephyr,GiulianoFranchetto/zephyr,kraj/zephyr,kraj/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,ldts/zephyr,explora26/zephyr,explora26/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,zephyrproject-rtos/zephyr,punitvara/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,punitvara/zephyr,punitvara/zephyr,finikorg/zephyr,kraj/zephyr,GiulianoFranchetto/zephyr,nashif/zephyr,kraj/zephyr