staging: fsl-mc: move dprc-driver private definitions out of mc-bus.h

Move definitions that are private to dprc-driver.c out of the
public mc-bus.h header.

Signed-off-by: Stuart Yoder <stuart.yoder@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>