drm/amdkfd: Use DECLARE_BITMAP

Use the generic mechanism to declare a bitmap instead of unsigned long.

It seems that "struct kfd_process.allocated_queue_bitmap" is unused.
Maybe it could be deleted instead.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>