wcn36xx: Add wcn36xx_smd_config_bss_v0

This commit adds wcn36xx_smd_config_bss_v0() as a step along the road of
functionally decomposing wcn36xx_smd_config_bss().

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200910150631.2178970-6-bryan.odonoghue@linaro.org