bus: fsl-mc: use raw spin lock to serialize mc cmds

Replace the spinlock that serializes the MC commands with a raw
spinlock. This is needed for the RT kernel because there are MC
commands sent in interrupt context.

Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
Link: https://lore.kernel.org/r/20200717154800.17169-3-ioana.ciornei@nxp.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>