net: dpaa: Convert to SPDX identifiers

This converts these files to use SPDX idenfifiers instead of license
text.

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Reviewed-by: Madalin Bucur <madalin.bucur@oss.nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>