mxgrub/mxgrub: Insert module *all_video*

With a system booted from UEFI, starting the Linux kernel from GRUB,
GRUB outputs

    error: not suitable video mode found
    booting in blind mode

and no Linux messages can be seen.

Jordan_U’s answer from #grub@irc.freenode.net:

> Are you using a manually written grub.cfg or one made by
> grub-mkconfig?
>
> If the former, add "insmod all_video" to your grub.cfg. That will
> allow grub to set up a video mode to then pass on to linux. IIRC, the
> text mode for UEFI is only intended for use by bootloaders, and thus
> should not be used by linux. I think that means that if grub doesn't
> pass a video mode to linux (which it needs video modules to be able to
> do) then you won't get early printk from the kernel, messages will
> only be displayed once native graphics drivers and KMS kicks in.

mxgrub/mxgrub

@@ -257,6 +257,9 @@ password_pbkdf2 root grub.pbkdf2.sha512.10000.A1168F03CC3CD47F79848E949584EA624F
 
 set default="$MARIUX_DEFAULT"
 load_env
+
+insmod all_video
+
 if [ -e /etc/local/USB.usb ]; then
 	set default="mariuxUSB"
 	menuentry "mariuxUSB" --unrestricted { save_env chosen ; linux /boot/bzImage.x86_64 crashkernel=256M root=LABEL=rootusb ro init=/bin/systemd audit=0 ; initrd /boot/grub/initramfs.igz }