staging/stradis: mark as "depends on BKL"

The stradis driver is on its way out, but it should still be marked
correctly as depending on the big kernel lock.  It could easily be
changed to not require it if someone decides to revive the driver and
port it to v4l2 in the process.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Sedat Dilek <sedat.dilek@googlemail.com>
Cc: Nathan Laredo <laredo@gnu.org>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>