MIPS: Alchemy: Merge PB1100/1500 support into DB1000 code.

The PB1100/1500 are similar to their DB-cousins but with a few
more devices on the bus.

This patch adds PB1100/1500 support to the existing DB1100/1500
code.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Cc: lnux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/4338/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>