MAINTAINERS: NXP add PetervdPerk-NXP bperseghetti

Add Peter van der Perk and Benjamin Perseghetti to NXP
collaborators for NXP Platforms and NXP HAL.

Also the new vmu_rt* board path to NXP Platforms group so PRs are
properly assigned.

Signed-off-by: Benjamin Perseghetti <bperseghetti@rudislabs.com>