habanalabs: avoid returning a valid handle if map_block() fails

map_block() sets the block id handle even if get_hw_block_id() fails,
and in this case it uses block id 0 which might be a valid id.
Modify it to set the handle only if get_hw_block_id() succeeds.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>