staging: dgnc: tty.c: edits var in init func for sparse

This patch edits the vaddr variable in dgnc_tty_init.
The variable gets set to board_t->re_map_membase. A
previous patch changed the re_map_membase variable's
marker and type. This patch makes sure that the
changes are consistent and that it doesn't cause
sparse warnings.

Signed-off-by: Lidza Louina <lidza.louina@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>