Fix the build target error when building sonic-rest-api (#10693)

Why I did it
Fix target target/debs/bullseye/sonic-rest-api_1.0.1_arm64.deb not existing issue, the correct target is target/debs/bullseye/sonic-rest-api_1.0.1_armhf.deb.
Fix issue: #9896

[ FAIL LOG START ] [ target/debs/stretch/sonic-rest-api_1.0.1_amd64.deb ]
[ REASON ] :      target/debs/stretch/sonic-rest-api_1.0.1_amd64.deb does not exist   NON-EXISTENT PREREQUISITES: 
[ FLAGS  FILE    ] : []

Author: xumia

rules/restapi.mk

@@ -1,6 +1,6 @@
 # sonic-rest-api package
 
-RESTAPI = sonic-rest-api_1.0.1_amd64.deb
+RESTAPI = sonic-rest-api_1.0.1_$(CONFIGURED_ARCH).deb
 $(RESTAPI)_SRC_PATH = $(SRC_PATH)/sonic-restapi
 $(RESTAPI)_DEPENDS += $(LIBHIREDIS_DEV) $(LIBNL3_DEV) $(LIBNL_GENL3_DEV) \
                             $(LIBNL_ROUTE3_DEV) $(LIBSWSSCOMMON_DEV) $(LIBSWSSCOMMON)