tty/vt: consolemap: saner variable names in con_set_default_unimap()

The function uses too vague variable names like i, j, k for iterators, p,
q, p1, p2 for pointers etc.

Rename all these, so that it is clear what is going on:
- dict: for dictionaries.
- d, r, g: for dir, row, glyph iterators -- these are unsigned now.
- dir, row: for directory and row pointers.
- glyph: for the glyph.
- and so on...

This is a lot of shuffling, but the result pays off, IMO.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220607104946.18710-30-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>