Make MPC8641's PCI/PCI-E driver a common driver for many FSL parts.

All of the PCI/PCI-Express driver and initialization code that
was in the MPC8641HPCN port has now been moved into the common
drivers/fsl_pci_init.c.  In a subsequent patch, this will be
utilized by the 85xx ports as well.

Common PCI-E IMMAP register blocks for FSL 85xx/86xx are added.

Also enable the second PCI-Express controller on 8641
by getting its BATS and CFG_ setup right.

Fixed a u16 vendor compiler warning in AHCI driver too.

Signed-off-by: Ed Swarthout <Ed.Swarthout@freescale.com>
Signed-off-by: Zhang Wei <wei.zhang@freescale.com>
Signed-off-by: Jon Loeliger <jdl@freescale.com>