fbuffer: Use a smaller cursor
fbuffer: Use a smaller cursor

Drawing the cursor in the frame buffer memory is a very, very
slow operation. So let's simply switch to a "underscore" cursor
instead of the full block cursor to save some precious cycles.

Signed-off-by: Thomas Huth <9e65be74847981e55b2564b6266c57d86d3bac05@redhat.com>
Signed-off-by: Alexey Kardashevskiy <ac1fc56530d7d037e1ea666f130daca22d72f964@ozlabs.ru>

aik/SLOF,qemu/SLOF,aik/SLOF,open-power-host-os/slof,stefanberger/SLOF-tpm,stefanberger/SLOF-tpm,open-power-host-os/slof,aik/SLOF,open-power-host-os/slof,qemu/SLOF,qemu/SLOF,stefanberger/SLOF-tpm,open-power-host-os/slof