powerpc/dts: Removed fsl,msi property from dts.

The association in the decice tree between PCI and MSI
using fsl,msi property was an artificial one and it does
not reflect the actual hardware.

Signed-off-by: Diana CRACIUN <Diana.Craciun@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>