powerpc/85xx: fix various PCI node compatible strings

Fix and/or improve the compatible strings of the PCI device tree nodes for
some Freescale SOCs.  This fixes some issues and improves consistency among
the SOCs.

Specifically:

1) The P1022 has a v1 PCIe controller, so the compatible property should just
say "fsl,mpc8548-pcie".  U-Boot does not look for "fsl,p1022-pcie", so it
wasn't fixing up the node.

2) The P4080 has a v2.1 PCIe controller, so add that version-specific string
to the device tree.  Update the kernel to also look for that string.
Currently, the kernel looks for "fsl,p4080-pcie" specifically, but
eventually that check should be deleted.

3) The P1010 device tree claims compatibility with v2.2 and v2.3, but that's
redundant.  No other device tree does this.  Remove the v2.2 string.

4) The kernel looks for both "fsl,p1023-pcie" and "fsl,qoriq-pcie-v2.2",
even though the P1023 device trees has always included both strings.  Remove
the search for "fsl,p1023-pcie".

Signed-off-by: Timur Tabi <timur@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>