wl18xx: change the low_band_component_type for HDK boards

Currently, all HDK boards use low_band_component_type 0x06.  In the
future this may change, but for now, we hardcode this value when the
board_type is set to HDK.

Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Arik Nemtsov <arik@wizery.com>