Revert "block: fix request_queue->flags initialization"

This reverts commit 2101aa5bb084931f22fa08cacd6d69c80afade7f which is
commit 60ea8226cbd5c8301f9a39edc574ddabcb8150e0 upstream.

To quote Ben:
	This is not needed, as there is no QUEUE_FLAG_BYPASS in 3.0.y.

To quote Tejun:
	I don't think it will break anything as it simply changes
	assignment to |= to avoid overwriting existing flags.  That
	said, any patch can break anything, so if possible it would be
	better to drop for 3.0.y.

So I'll revert this to be safe.

Cc: Tejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>