mmc: sdhci-acpi: Clear amd_sdhci_host on reset

mmc: sdhci-acpi: Clear amd_sdhci_host on reset

The commit f01a208e163fa ("mmc: sdhci-acpi: Fix HS400 tuning for AMDI0040")
broke resume for eMMC HS400. When the system suspends the eMMC controller
is powered down. So, on resume we need to reinitialize the controller.
Although, amd_sdhci_host was not getting cleared, so the DLL was never
re-enabled on resume. This results in HS400 being non-functional.

To fix the problem, this change clears the tuned_clock flag, clears the
dll_enabled flag and disables the DLL on reset.

Fixes: f01a208e163fa ("mmc: sdhci-acpi: Fix HS400 tuning for AMDI0040")
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20200831150517.1.I93c78bfc6575771bb653c9d3fca5eb018a08417d@changeid
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>