staging: wilc1000: remove function pointer os_wait

This patch removes function pointer os_wait which is pointer of
linux_wlan_lock_timeout and just call the real name function directly.
Remove also static from linux_wlan_lock_timeout declaration.
As os_wait is deleted, structure wilc_wlan_os_func_t is useless. Delete
wilc_wlan_os_func_t, os_func and it's related codes.

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