wcn36xx: Move BSS parameter setup to wcn36xx_smd_set_bss_params()

This commit moves BSS parameter setup to a separate function
wcn36xx_smd_set_bss_params(). This will allow for further functional
decomposition and fewer kzalloc() operations in subsequent patches.

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/20200910150631.2178970-4-bryan.odonoghue@linaro.org