wl12xx: correct printk format warnings

Fixes warnings:
  drivers/net/wireless/wl12xx/main.c:87: warning: int format, different
    type arg (arg 2)
  drivers/net/wireless/wl12xx/main.c: In function `wl12xx_fetch_nvs':
  drivers/net/wireless/wl12xx/main.c:125: warning: int format, different
    type arg (arg 2)
  drivers/net/wireless/wl12xx/wl1251.c: In function 'wl1251_upload_firmware':
  drivers/net/wireless/wl12xx/wl1251.c:94: warning: int format, different
    type arg (arg 2)
  drivers/net/wireless/wl12xx/wl1251.c:141: warning: int format, different
    type arg (arg 2)

Signed-off-by: Bob Copeland <me@bobcopeland.com>
Acked-by: Kalle Valo <kalle.valo@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>