staging: wilc1000: remove function pointer cfg_wid_get

Remove function pointer cfg_wid_get and call the function
wilc_wlan_cfg_get_wid instead. Remove static from the function declaration.

Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Tony Cho <tony.cho@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>