lib/fonts: Store font data as font_data_t; update consoles

lib/fonts: Store font data as font_data_t; update consoles

Store font data as pointer to font_data_t instead of unsigned char.
Update consoles.

Pointers to font data refer to the raw data. There is a hidden header
before the data that contains additional state. Document the existing
layout and semantics of font_data_t.

The data field in struct vc_font can be used by any console. Therefore
it still points to plain data without the additional header. Fbcon sets
its value from struct fbcon_display.fontdata. Hence, update the size
test in fbcon_resize() to use struct fbcon_display.fontdata instead of
struct vc_font.data.

v3:
- fix typos (Helge)
v2:
- 'Font lookup' -> 'Font description' in <linux/font.h>

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Helge Deller <deller@gmx.de>