MAINTAINERS: Change fsl-qoriq, mpc86xx, mpc85xx maintainers

Change maintainers to Priyanka Jain for fsl-qoriq, mpc85xx

Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>
Acked-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>