MIPS: Octeon: Update L2 Cache code for CN63XX

The CN63XX has a different L2 cache architecture.  Update the helper
functions to reflect this.

Some joining of split lines was also done to improve readability, as
well as reformatting of comments.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Patchwork: http://patchwork.linux-mips.org/patch/1663/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>