Fix size check for devices with multiple groups

The old code calls check-sum-of-partition-sizes within a foreach
loop, causing syntax error:
... fi partition_size_list=...

Add a semicolon after fi to fix this.
Test: build with multiple groups, each group with a partition in it

Change-Id: Ic4387408f3efc1744871619c300546765c678a61
diff --git a/core/Makefile b/core/Makefile
index f6a246b..f8cf882 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -3122,7 +3122,7 @@
   else \
     echo "The sum of sizes of [$(strip $(3))] is within $(strip $(1)):"; \
     echo $${sum_sizes_expr} '==' $$(( $${sum_sizes_expr} )) '<=' "$(2)" '==' $$(( $(2) )); \
-  fi
+  fi;
 endef
 
 define check-all-partition-sizes-target