drivers: net: fsl-mc: remove explicit cast

Remove all the explicit casts from the void* returned by calloc.
With this we also improve a bit the length of those lines and there is
no need to split the assignment.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>