MIPS: qca956x: Enable AP151 target support

The following features are enabled ,
1) AP151 target specific configs are added ( mainly ethernet )
2) AP151 and AP152 share a common configuration file & Makefile
with minimal changes between them. Support for avoiding the conflict
between them is implemented.

Change-Id: Ia71b20199d43cd29ff214c1258e4b15fcd55cb6b
Signed-off-by: Prabhu Jayakumar <pjayak@codeaurora.org>
16 files changed