scripts: fixup qemustart for new x86 image names

qemustart allows easy testing of created images via `qemu`. The script
automatically selects created images and can setup e.g. networks.

As the x86 target now uses the generic image.mk the profile appears also
in the image name, this is *generic*.

Add the profile name to the qemustart script so it still finds the file.

Signed-off-by: Paul Spooren <mail@aparcar.org>

scripts/qemustart

@@ -255,7 +255,7 @@ start_qemu_x86() {
 	local mach="${o_mach:-pc}"
 
 	[ -n "$rootfs" ] || {
-		rootfs="$o_bindir/openwrt-$o_target-${o_subtarget%-*}-combined-ext4.img"
+		rootfs="$o_bindir/openwrt-$o_target-${o_subtarget%-*}-generic-ext4-combined.img"
 		if [ ! -f "$rootfs" -a -s "$rootfs.gz" ]; then
 			gunzip "$rootfs.gz"
 		fi