staging: wilc1000: remove function pointer mac_indicate

No need for a pointer to a function. Just call linux_wlan_mac_indicate.
Remove mac_indicate and also wilc_wlan_indicate_func_t since no members in it.
Variable indicate_func is not used so delete it and related codes.
Finally remove static from the function linux_wlan_mac_indicate.

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