mmc: sdhci-brcmstb: Enable Clock Gating to save power

[ Upstream commit 6bcc55fe ]

Enabling this feature will allow the controller to stop the bus
clock when the bus is idle. The feature is not part of the standard
and is unique to newer Arasan cores and is enabled with a bit in a
vendor specific register. This feature will only be enabled for
non-removable devices because they don't switch the voltage and
clock gating breaks SD Card volatge switching.

Signed-off-by: Al Cooper <alcooperx@gmail.com>
Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20220427180853.35970-3-kdasu.kdev@gmail.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Stable-dep-of: 56baa208 ("mmc: sdhci-brcmstb: Fix SDHCI_RESET_ALL for CQHCI")
Signed-off-by: Sasha Levin <sashal@kernel.org>