habanalabs: set command buffer host VA dynamically

Set the addresses for userspace command buffer dynamically
instead of hard-coded. There is no reason for it to
be hard-coded.

Signed-off-by: Dafna Hirschfeld <dhirschfeld@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>