wl12xx: fix separate-object-folder builds

Make this go away (happens when building with a separate object
directory):

Assembler messages:
Fatal error: can't create drivers/net/wireless/wl12xx/.tmp_wl12xx_platform_data.o: No such file or directory
drivers/net/wireless/wl12xx/wl12xx_platform_data.c: In function 'wl12xx_get_platform_data':
drivers/net/wireless/wl12xx/wl12xx_platform_data.c:28: error: cannot open drivers/net/wireless/wl12xx/.tmp_wl12xx_platform_data.gcno
drivers/net/wireless/wl12xx/wl12xx_platform_data.c:28: confused by earlier errors, bailing out

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Signed-off-by: Ohad Ben-Cohen <ohad@wizery.com>

drivers/net/wireless/Makefile

@@ -50,7 +50,6 @@ obj-$(CONFIG_ATH_COMMON)	+= ath/
 obj-$(CONFIG_MAC80211_HWSIM)	+= mac80211_hwsim.o
 
 obj-$(CONFIG_WL12XX)	+= wl12xx/
-# small builtin driver bit
-obj-$(CONFIG_WL12XX_PLATFORM_DATA)	+= wl12xx/wl12xx_platform_data.o
+obj-$(CONFIG_WL12XX_PLATFORM_DATA)	+= wl12xx/
 
 obj-$(CONFIG_IWM)	+= iwmc3200wifi/

drivers/net/wireless/wl12xx/Makefile

@@ -16,3 +16,6 @@ wl1271-$(CONFIG_NL80211_TESTMODE)	+= wl1271_testmode.o
 obj-$(CONFIG_WL1271)	+= wl1271.o
 obj-$(CONFIG_WL1271_SPI)	+= wl1271_spi.o
 obj-$(CONFIG_WL1271_SDIO)	+= wl1271_sdio.o
+
+# small builtin driver bit
+obj-$(CONFIG_WL12XX_PLATFORM_DATA)	+= wl12xx_platform_data.o