powerpc/mpc8548cds: Code cleanup and refactoring

- Rework tlb and law tables.
- PCI2 is not available on MPC8548CDS, so remove it.
- Move the memory map to the board config file.
- Rewrite the board info according to the manual.
- Remove unnecessary macros and redefine some macros to align with other boards.
- Fix some typos.

Signed-off-by: Zhao Chenhui <chenhui.zhao@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>