misc: deb: Fix the ServiceVM kernel line in ACRN grub entry

After replacing partitioned ACRN deb with shared deb, the stale
multiboot module for ACPI1.bin was left in ACRN grub entry because it
was taken as kernel image.

Tracked-On: #7400
Signed-off-by: Calvin Zhang <calvinzhang.cool@gmail.com>

misc/packaging/acrn-hypervisor.postinst

@@ -26,7 +26,12 @@ done < <(blkid |grep ext4 |grep ${type})
 
 filename="/etc/grub.d/40_custom"
 
-kernelimg=$(grep module ${filename} | tail -1 || true)
+if ls /boot/vmlinuz*acrn-service-vm* 1> /dev/null 2>&1;then
+    service_vm_kernel=$(ls -tr /boot/vmlinuz-*acrn-service-vm* | tail -1)
+else
+    service_vm_kernel=$(ls /boot/vmlinuz-* | tail -1)
+fi
+kernelimg="module2 $service_vm_kernel Linux_bzImage"
 
 if [ $SCENARIO == shared ];then
     cat>"${filename}"<<EOF