kernel-install: use up to date initramfs

During installation, /usr/lib/kernel/install.d/50-dracut.install
generate initramfs in $BOOT_DIR_ABS. It is important to use that one,
even if there is one in /boot/initramfs-*.img already, because it was
generated later and contains all required config files (including
keyboard layout for entering LUKS passphrase).

This fixes d1f3be0eed "kernel-install:
avoid creating initramfs multiple times".

Fixes QubesOS/qubes-issues#3234

system-config/kernel-grub2.install

@@ -6,12 +6,12 @@ BOOT_DIR_ABS="$3"
 
 case "$COMMAND" in
     add)
+        # use newer image if available
+        if [ -e "$BOOT_DIR_ABS"/initrd ]; then
+            cp -u "$BOOT_DIR_ABS"/initrd "/boot/initramfs-${KVER}.img"
+        fi
         if [ ! -e "/boot/initramfs-${KVER}.img" ]; then
-            if [ -e "$BOOT_DIR_ABS"/initrd ]; then
-                cp "$BOOT_DIR_ABS"/initrd "/boot/initramfs-${KVER}.img"
-            else
-                dracut "/boot/initramfs-${KVER}.img" "$KVER"
-            fi
+            dracut "/boot/initramfs-${KVER}.img" "$KVER"
         fi
         ;;
     remove)