[build]: do not override ENABLE_SYNCD_RPC in rules/config (#2151)

Signed-off-by: Guohan Lu <gulv@microsoft.com>

Makefile.work

@@ -94,7 +94,7 @@ SONIC_BUILD_INSTRUCTION :=  make \
                            ENABLE_DHCP_GRAPH_SERVICE=$(ENABLE_DHCP_GRAPH_SERVICE) \
                            SHUTDOWN_BGP_ON_START=$(SHUTDOWN_BGP_ON_START) \
                            SONIC_ENABLE_PFCWD_ON_START=$(ENABLE_PFCWD_ON_START) \
-                           ENABLE_SYNCD_RPC=$(ENABLE_SYNCD_RPC) \
+                           SONIC_ENABLE_SYNCD_RPC=$(ENABLE_SYNCD_RPC) \
                            PASSWORD=$(PASSWORD) \
                            USERNAME=$(USERNAME) \
                            SONIC_BUILD_JOBS=$(SONIC_BUILD_JOBS) \

slave.mk

@@ -70,6 +70,10 @@ ifeq ($(SONIC_ENABLE_SYSTEM_TELEMETRY),y)
 ENABLE_SYSTEM_TELEMETRY = y
 endif
 
+ifeq ($(SONIC_ENABLE_SYNCD_RPC),y)
+ENABLE_SYNCD_RPC = y
+endif
+
 include $(RULES_PATH)/config
 include $(RULES_PATH)/functions
 include $(RULES_PATH)/*.mk