drm/log: Add integer scaling support

Add a module parameter, to increase the font size for HiDPI screen.
Even with CONFIG_FONT_TER16x32, it can still be a bit small to read.
In this case, adding drm_log.scale=2 to your kernel command line will
double the character size.

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20241204160014.1171469-7-jfalempe@redhat.com