lib/fonts: Create font_data_t from struct console_font with font_data_import()

lib/fonts: Create font_data_t from struct console_font with font_data_import()

Add font_data_import() and update consoles to use it.

The implementation of font_data_import() is based on code from fbcon,
which supports overflow checks and crc32 checksums. Fbcon uses the crc32
checksum.

Newport_con now implements the same overflow checks as fbcon. As before,
this console does not support checksums, which are optional. Newport_con
can now also handle input font data with a vertical pitch other than 32
bytes. (The vertical pitch is the offset between two glyphs in the font
data.)

As an internal change, remove the const qualifier from the data field
if struct font_data. This allows font_data_import() to write the data
without type casting. For all users of the font data via font_data_t,
the stored data is still read only.

v3:
- fix typos

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