tty/vt: consolemap: make p1 increment less confusing in con_get_unimap()

p2 is already incremented like this few lines below, so do the same for
p1. This makes the code easier to follow.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220607104946.18710-15-jslaby@suse.cz


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>