staging: fsl-mc: get version of root dprc from MC hardware

The root dprc is discovered as a platform device in the device tree.  The
version of that dprc was previously set using hardcoded values from the API
header in the kernel).  This patch removes the use of the hardcoded version
numbers and instead reads the actual dprc version from the hardware.

Signed-off-by: Itai Katz <itai.katz@nxp.com>
(Stuart: resolved merge conflict, updated commit subject/log)
Signed-off-by: Stuart Yoder <stuart.yoder@nxp.com>
Acked-by: German Rivera <german.rivera@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>