retuning mode is 1. This flag is used afterwards whenever
needs to decide if the host is currently using a retuning timer.

This flag is cleared when the card is removed in sdhci_reinit.

The set/clear of the flag and the start/stop of the retuning timer is
associated with the card's init/remove time, so there is no need to
touch it when the host is to be removed as at that time the card should
have already been removed.

Signed-off-by: Aaron Lu <aaron.lu@amd.com>
Reviewed-by: Girish K S <girish.shivananjappa@linaro.org>
Reviewed-by: Philip Rakity <prakity@marvell.com>
Signed-off-by: Chris Ball <cjb@laptop.org>