drivers: mmc: sdhci_am654: Add the quirk to set TESTCD bit

drivers: mmc: sdhci_am654: Add the quirk to set TESTCD bit

The ARASAN MMC controller on Keystone 3 class of devices need the SDCD
line to be connected for proper functioning. Similar to the issue pointed
out in sdhci-of-arasan.c driver, commit 3794c542641f ("mmc:
sdhci-of-arasan: Set controller to test mode when no CD bit").

In cases where this can't be connected, add a quirk to force the
controller into test mode and set the TESTCD bit. Use the flag
"ti,fails-without-test-cd", to implement this above quirk when required.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Link: https://lore.kernel.org/r/20220425063120.10135-3-a-govindraju@ti.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>