dpaa2-switch: fix size of the dma_unmap

The size of the DMA unmap was wrongly put as a sizeof of a pointer.
Change the value of the DMA unmap to be the actual macro used for the
allocation and the DMA map.

Fixes: 1110318d

 ("dpaa2-switch: add tc flower hardware offload on ingress traffic")
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Link: https://lore.kernel.org/r/20231212164326.2753457-2-ioana.ciornei@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>