arm: mach-k3: introduce generic board detction kconfig option

For non TI boards it is not possible to enable the do_board_detect()
call as TI_I2C_BOARD_DETECT is defined in board/ti/common/Kconfig.

I want to use do_board_detect() to dectect boards and properties based
on some SPI communication with a FPGA.

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>