sparc has a 'btext' font used for the console which is almost identical
to the shared font_sun8x16, so use it rather than duplicating the data.

They were actually identical until about a decade ago when
   commit bcfbeece ("drivers: console: font_: Change a glyph from
                        "broken bar" to "vertical line"")

which changed the | in the shared font to be a solid
bar rather than a broken bar.  That's the only difference.

This was originally spotted by PMD which noticed that PPC does
the same thing with the same data, and they also share a bunch
of functions to manipulate the data.

Tested very lightly with a boot without FS in qemu.
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Link: https://lore.kernel.org/r/20230807010914.799713-1-linux@treblig.org