ppc4xx: Big lwmon5 board support rework/update

This patch brings the lwmon5 board support up-to-date. Here a
summary of the changes:

lwmon5 board port related:
- GPIO's changed to control the LSB transmitter
- Reset USB PHY's upon power-up
- Enable CAN upon power-up
- USB init error workaround (errata CHIP_6)
- EBC: Enable burstmode and modify the timings for the GDC memory
- EBC: Speed up NOR flash timings

lwmon5 board POST related:
- Add FPGA memory test
- Add GDC memory test
- DSP POST reworked
- SYSMON POST: Fix handling of negative temperatures
- Add output for sysmon1 POST
- HW-watchdog min. time test reworked

Additionally some coding-style changes were done.

Signed-off-by: Sascha Laue <sascha.laue@liebherr.com>
Signed-off-by: Stefan Roese <sr@denx.de>