Fix CONFIG_MODULE_TESTS=y build without CONFIG_P2P=y

Signed-off-by: Jouni Malinen <j@w1.fi>

wpa_supplicant/Makefile

@@ -1499,6 +1499,9 @@ OBJS += ../src/common/common_module_tests.o
 ifdef CONFIG_WPS
 OBJS += ../src/wps/wps_module_tests.o
 endif
+ifndef CONFIG_P2P
+OBJS += ../src/utils/bitfield.o
+endif
 endif
 
 OBJS += ../src/drivers/driver_common.o