wl1271: Add structure for firmware configuration values

In order to make the firmware configuration more manageable, collect
hardcoded configuration values into one data structure, and set default values
there.

Add the SoftGemini BT/WLAN coex paramters into the config structure.

Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Reviewed-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>