remove unused make define

Change-Id: Ia9ef8ce705803df06cf1e4c3ac9731ce69e5e6c5
diff --git a/firmware/Makefile b/firmware/Makefile
index fa72bd3..0f70bf4 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -124,8 +124,6 @@
 # only applicable for qmod board
 ALLOW_PEER_ERASE?=0
 
-DEBUG_PHONE_SNIFF?=0
-
 #CFLAGS+=-DUSB_NO_DEBUG=1
 
 # Optimization level, put in comment for debugging
@@ -167,7 +165,7 @@
 #CFLAGS += -Wa,-a,-ad
 CFLAGS += -D__ARM
 CFLAGS += --param max-inline-insns-single=500 -mcpu=cortex-m3 -mthumb # -mfix-cortex-m3-ldrd
-CFLAGS += -ffunction-sections -g $(OPTIMIZATION) $(INCLUDES) -D$(CHIP) -DTRACE_LEVEL=$(TRACE_LEVEL) -DDEBUG_PHONE_SNIFF=$(DEBUG_PHONE_SNIFF) -DALLOW_PEER_ERASE=$(ALLOW_PEER_ERASE)
+CFLAGS += -ffunction-sections -g $(OPTIMIZATION) $(INCLUDES) -D$(CHIP) -DTRACE_LEVEL=$(TRACE_LEVEL) -DALLOW_PEER_ERASE=$(ALLOW_PEER_ERASE)
 CFLAGS += -DGIT_VERSION=\"$(GIT_VERSION)\"
 CFLAGS += -DBOARD=\"$(BOARD)\" -DBOARD_$(BOARD)
 CFLAGS += -DAPPLICATION=\"$(APP)\" -DAPPLICATION_$(APP)