All avs drivers have now been moved to their corresponding soc specific
directories. Additionally, they don't depend on the POWER_AVS Kconfig
anymore. Therefore, let's simply drop the drivers/power/avs directory
altogether.
Cc: Nishanth Menon
Signed-off-by: Ulf Hansson
Reviewed-by: Nishanth Menon
Signed-off-by: Rafael J. Wysocki