cris: remove unused global_flush_tlb

global_flush_tlb is declared but never used.

Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Cc: Mikael Starvik <starvik@axis.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>