drivers/video/console/fbcon_cw.c: fix compiler warning in cw_update_attr

With make W=1 we get

  drivers/video/console/fbcon_cw.c: In function `cw_update_attr':
  drivers/video/console/fbcon_cw.c:30:8: warning: variable `t' set but not used [-Wunused-but-set-variable]

fixed by removing as since its used nowhere

Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>