staging: nvec: fix the '&&' vs '&' typo in nvec_toggle_global_events()

Fix the '&&' vs '&' typo.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-By: Marc Dietrich <marvin24@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>