dt-bindings: sdhci-omap: Update binding for legacy SoCs

Let's add compatible values for the legacy SoCs so we can continue
deprecating omap_hsmmc in favor of sdhci-omap driver.

For omap5, we want to have a separate compatible from omap4 for the
additional features available on omap5. AFAIK ti81 can just use the
omap4 compatible.

Cc: [e-mail]
Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Tony Lindgren <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Ulf Hansson <[e-mail]>

Documentation/devicetree/bindings/mmc/sdhci-omap.txt

···
 For UHS devices which require tuning, the device tree should have a "cpu_thermal" node which maps to the appropriate thermal zone. This is used to get the temperature of the zone during tuning.
 
 Required properties:
-- compatible: Should be "ti,dra7-sdhci" for DRA7 and DRA72 controllers
+- compatible: Should be "ti,omap2430-sdhci" for omap2430 controllers
+	      Should be "ti,omap3-sdhci" for omap3 controllers
+	      Should be "ti,omap4-sdhci" for omap4 and ti81 controllers
+	      Should be "ti,omap5-sdhci" for omap5 controllers
+	      Should be "ti,dra7-sdhci" for DRA7 and DRA72 controllers
 	      Should be "ti,k2g-sdhci" for K2G
 	      Should be "ti,am335-sdhci" for am335x controllers
 	      Should be "ti,am437-sdhci" for am437x controllers