cacheinfo: Set cache 'id' based on DT data

Use the minimum CPU h/w id of the CPUs associated with the cache for the
cache 'id'. This will provide a stable id value for a given system. As
we need to check all possible CPUs, we can't use the shared_cpu_map
which is just online CPUs. As there's not a cache to CPUs mapping in DT,
we have to walk all CPU nodes and then walk cache levels.

The cache_id exposed to user-space has historically been 32 bits, and
is too late to change. This value is parsed into a u32 by user-space
libraries such as libvirt:
https://github.com/libvirt/libvirt/blob/master/src/util/virresctrl.c#L1588

Give up on assigning cache-id's if a CPU h/w id greater than 32 bits
is found.

match_cache_node() does not make use of the __free() cleanup helpers
because of_find_next_cache_node(prev) does not drop a reference to prev,
and its too easy to accidentally drop the reference on cpu, which belongs
to for_each_of_cpu_node().

Cc: "Rafael J. Wysocki" <[email protected]>
Signed-off-by: Rob Herring <[email protected]>
[ ben: converted to use the __free cleanup idiom ]
Signed-off-by: Ben Horgan <[email protected]>
[ morse: Add checks to give up if a value larger than 32 bits is seen. ]
Signed-off-by: James Morse <[email protected]>
Reviewed-by: Jonathan Cameron <[email protected]>
Reviewed-by: Gavin Shan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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