Conditionalise ARM specific compiler option

See I92ed31bff30a5011e9e0e86c7c90ca140be2f4dc
for similar issues in building Broadcom wlan.

Change-Id: I71e71a78823537917e5089b90c3cda4bdccdbaef
diff --git a/qcwcn/wpa_supplicant_8_lib/Android.mk b/qcwcn/wpa_supplicant_8_lib/Android.mk
index 802454c..df715ae 100644
--- a/qcwcn/wpa_supplicant_8_lib/Android.mk
+++ b/qcwcn/wpa_supplicant_8_lib/Android.mk
@@ -39,8 +39,10 @@
 WPA_SRC_FILE += driver_cmd_nl80211.c
 endif
 
+ifeq ($(TARGET_ARCH),arm)
 # To force sizeof(enum) = 4
 L_CFLAGS += -mabi=aapcs-linux
+endif
 
 ifdef CONFIG_ANDROID_LOG
 L_CFLAGS += -DCONFIG_ANDROID_LOG