wl18xx: avoid some -Wformat warnings

  CC      drivers/net/wireless/ti/wl18xx/main.o
drivers/net/wireless/ti/wl18xx/main.c: In function ‘wl18xx_conf_init’:
drivers/net/wireless/ti/wl18xx/main.c:1024:3: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘long unsigned int’ [-Wformat]
drivers/net/wireless/ti/wl18xx/main.c:1024:3: warning: format ‘%d’ expects argument of type ‘int’, but argument 3 has type ‘size_t’ [-Wformat]

Signed-off-by: John W. Linville <linville@tuxdriver.com>