staging: wilc1000: assign pointer of g_linux_wlan to sdio device data

This patch assigns wl pointer to sdio device data. The global variable
g_linux_wlan will be removed finally.

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