arm64: defconfig: Enable TI ADC driver

Enable ADC driver to be built as a module which will
add support for ADC in TI K3 specific SoCs.

Signed-off-by: Bhavya Kapoor <b-kapoor@ti.com>
Reviewed-by: Manorit Chawdhry <m-chawdhry@ti.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>