Revert "MIPS: octeon: Remove vestiges of CONFIG_CAVIUM_RESERVE32"

This reverts commit e98b461b

.

We actually have been using the CONFIG_CAVIUM_RESERVE32 and previous patch
defined it in the corresponding Kconfig.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>