staging: fsl-mc: improve naming of source files

The mc- prefix on the source files names of some internal components
of the fsl-mc bus driver makes things less clear that they could be.
The string "mc" generally refers to hardware-- the physical DPAA
'management complex'.  Names like "mc-allocator.c" have nothing to
with the "MC" hardware per se.  Improve clarity by using the prefix
string "fsl-mc" instead which is what we are calling this bus.

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