makefile: place firmware for VM in correct dir

kernel.spec

@@ -419,7 +419,7 @@ mkfs -t ext3 -F /tmp/qubes-modules-%kernelrelease.img > /dev/null
 mount /tmp/qubes-modules-%kernelrelease.img /tmp/qubes-modules-%kernelrelease -o loop
 cp -a -t /tmp/qubes-modules-%kernelrelease %vm_install_dir/modules/%kernelrelease
 mkdir /tmp/qubes-modules-%kernelrelease/firmware
-cp -a -t /tmp/qubes-modules-%kernelrelease %vm_install_dir/modules/firmware/%kernelrelease
+cp -a -t /tmp/qubes-modules-%kernelrelease/firmware %vm_install_dir/modules/firmware/%kernelrelease
 umount /tmp/qubes-modules-%kernelrelease
 rmdir /tmp/qubes-modules-%kernelrelease
 mv /tmp/qubes-modules-%kernelrelease.img %vm_install_dir/modules.img