Add support for configuring the Self Refresh Power Down (SRPD)
inactivity timeout on Broadcom STB chips. This is used to conserve power
when the DRAM activity is reduced.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220812222533.2428033-4-f.fainelli@gmail.com