mmc: am654_sdhci: Add tuning algorithm for delay chain

Currently the sdhci_am654 driver only supports one tuning
algorithm which should be used only when DLL is enabled. The
ITAPDLY is selected from the largest passing window and the
buffer is viewed as a circular buffer.

The new tuning algorithm should be used when the delay chain
is enabled; the ITAPDLY is selected from the largest passing
window and the buffer is not viewed as a circular buffer.

This implementation is based off of the following paper: [1].

Also add support for multiple failing windows.

[1] https://www.ti.com/lit/an/spract9/spract9.pdf



Fixes: a759abf5 ("mmc: am654_sdhci: Add support for software tuning")
Signed-off-by: Judith Mendez <jm@ti.com>