powerpc: Fix missing L2 cache size in /sys/devices/system/cpu

[ Upstream commit f7e9e358 ]

This problem appears to have been introduced in 2.6.29 by commit
93197a36 "Rewrite sysfs processor cache info code".

This caused lscpu to error out on at least e500v2 devices, eg:

  error: cannot open /sys/devices/system/cpu/cpu0/cache/index2/size: No such file or directory

Some embedded powerpc systems use cache-size in DTS for the unified L2
cache size, not d-cache-size, so we need to allow for both DTS names.
Added a new CACHE_TYPE_UNIFIED_D cache_type_info structure to handle
this.

Fixes: 93197a36 ("powerpc: Rewrite sysfs processor cache info code")
Signed-off-by: Dave Olson <olson@cumulusnetworks.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>