driver: net: fsl-mc: Memset dprc_cfg before configuring

All fields of struct dprc_cfg are not being configured while creating
child container. "Not" configured fields are assumed to be 0.

So memset dprc_cfg before configuring the fields.

Signed-off-by: Itai Katz <itai.katz@nxp.com>
Signed-off-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>