commit 0a5f6e9d upstream.

This is a port of cedb655a
to older asics.  Fixes a possible divide by 0 if the harvest
register is invalid.

v2: drop some additional harvest munging.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>