staging: fsl-mc: improve pr_* messages

define pr_fmt so non dev_* messages will have an fsl-mc prefix
and remove "fsl-mc" from messages where it would now be redundant

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