powerpc/44x: Add additional device support for APM821xx SoC and Bluestone board

This patch updates the dts file for bluestone board with support:
- UART1
- L2 cache
- NAND with NDFC
- PCI-E

Signed-off-by: Vinh Nguyen Huu Tuong <vhtnguyen@apm.com>
Signed-off-by: Josh Boyer <jwboyer@gmail.com>