bus: fsl-mc: change mc_command in fsl_mc_command

The "struct mc_command" is a very generic name for a global
kernel structure. Change its name in "struct fsl_mc_command".

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>