drm/nouveau: Fix fbcon corruption with font width not divisible by 8

NV50 is nice and has a switch that autoaligns stuff for us. Pre-NV50,
we need to align input bitmap width manually.

Signed-off-by: Marcin Kościelnicki <koriakin@0x04.net>
Signed-off-by: Francisco Jerez <currojerez@riseup.net>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>