Fix vmx second stage v2

Revised to be (hopefully) less intrusive.

This fixes GRUB2 second boot, KIWILinuxRC.sh was expecting vga=<mode> kernel parameter, this wasn't passed due to 32 bit mode / GRUB2 using gfxpayload on the first boot.  Verified by checking /proc/cmdline and reading grub2.info (sub-sections on Linux and gfxpayload).

This attempts to fix a reasonable build time default.

Note - the setting of DEFAULT_VGA should maintain the existing default unless the build configuration sets vga= on type info, if it does that should be used.