Partially revert "vt: register the memory regions used by the vt drivers"

Revert the EFI part of r276064 until I can test it properly on a real EFI
system. This was causing problems to people booting using UEFI and vt.

Reported by:	O. Hartmann <ohartman@zedat.fu-berlin.de>


git-svn-id: svn+ssh://svn.freebsd.org/base/head@276405 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
vt_vga: fix an off-by-one error

This correctly sets the end of the memory region registered by vt_vga.

Reported by:	marius


git-svn-id: svn+ssh://svn.freebsd.org/base/head@276406 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f