qemu-ga: Two MSI related cosmetic changes

Signed-off-by: Leonid Bloch <leonid@daynix.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
diff --git a/Makefile b/Makefile
index 340d9c8..9a4c3c6 100644
--- a/Makefile
+++ b/Makefile
@@ -295,7 +295,7 @@
 ifdef QEMU_GA_MSI_ENABLED
 QEMU_GA_MSI=qemu-ga-$(ARCH).msi
 
-msi: ${QEMU_GA_MSI}
+msi: $(QEMU_GA_MSI)
 
 $(QEMU_GA_MSI): qemu-ga.exe