staging: fsl-mc: update Kconfig dependency

The Kconfig dependency previously included ARM64, which is not
strictly correct.  Change it to ARCH_LAYERSCAPE which is the
SoC platform that includes the DPAA2 hardware.

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