Staging: rt2860: clean up & => &&

a4_exists is an integer used as a boolean type so the original code
works.  But all the other conditions use && and this makes it
consistent.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>