It turns out that there are only 2 in-tree platforms which use MPICs
which are not "primary": IBM Cell and PowerMac. To reduce the
complexity of the typical board setup code, invert the MPIC_PRIMARY bit
into MPIC_SECONDARY.
Signed-off-by: Kyle Moffett <Kyle.D.Moffett@boeing.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>