vt_buffer: drop console buffer copying optimisations

vt_buffer: drop console buffer copying optimisations

These two copy to/from VGA memory, however on the Silicon
Motion SMI750 VGA card on a 64-bit system cause console corruption.

This is due to the hw being buggy and not handling a 64-bit transaction
correctly.

We could try and create a 32-bit version of these routines,
but I'm not sure the optimisation is worth much today.

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1132826

Tested-by: Huawei engineering.
Signed-off-by: Dave Airlie <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Hurley <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>