efi_loader: Some console improvements for vidconsole

1) use fputs() to reduce cache flushes from once-per-char to
   once-per-string
2) handle \r, \t, and \b in addition to just \n for tracking
   cursor position
3) cursor row/col are zero based, not one based

Signed-off-by: Rob Clark <robdclark@gmail.com>
[agraf: s/unsigned/unsigned int/]
Signed-off-by: Alexander Graf <agraf@suse.de>