cpufreq: ti-cpufreq: Allow backward compatibility for efuse syscon

The AM625 syscon for efuse was being taken earlier from the wkup_conf node
where the entire wkup_conf was marked as "syscon". This is wrong and will
be fixed in the devicetree. However, whenever that does happen will end up
breaking this driver for that device because of the change in efuse offset.

Hence, to avoid breaking any sort of backward compatibility of devicetrees
use a quirk to distinguish and accordingly use 0x0 offset for the new
syscon node.

Suggested-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Dhruva Gole <d-gole@ti.com>
Reviewed-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>