wifi: wcn36xx: Move capability bitmap to string translation function to firmware.c

Move wcn36xx_get_cap_name() function in main.c into firmware.c as
wcn36xx_firmware_get_cap_name().

Reviewed-by: Loic Poulain <loic.poulain@linaro.org>
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20220727161655.2286867-4-bryan.odonoghue@linaro.org