[platform][riscv-virt] added support for QEMU's riscv 'virt' machine

The virt machine is a generic target, much like the arm virt machine.
Intended to be simple to use and a good target to run large systems like
linux on. At the moment simply support booting and simple uart and timer
support.

scripts/do-qemuarm

@@ -103,9 +103,9 @@ fi
 MAKE_VARS=""
 
 if [ $DO_CMPCTMALLOC == 1 ]; then
-	MAKE_VARS=LK_HEAP_IMPLEMENTATION=cmpctmalloc
+    MAKE_VARS=LK_HEAP_IMPLEMENTATION=cmpctmalloc
 elif [ $DO_MINIHEAP == 1 ]; then
-	MAKE_VARS=LK_HEAP_IMPLEMENTATION=miniheap
+    MAKE_VARS=LK_HEAP_IMPLEMENTATION=miniheap
 fi
 
 $DIR/make-parallel $MAKE_VARS $PROJECT &&