staging: dgnc: dgnc_driver: remove all occurences of trcbuf_size

This patch removes the variable trcbuf_size given there is no real
use for it anymore. All of the debug variables in this driver is
basically dead code.

Signed-off-by: Aya Mahfouz <mahfouz.saif.elyazal@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>