ehci-platform: Change compatible string from usb-ehci to generic-ehci

The initial versions of the devicetree enablement patches for ehci-platform
used "ehci-platform" as compatible string. However this was disliked by various
reviewers because the platform bus is a Linux invention and devicetree is
supposed to be OS agnostic. After much discussion I gave up, added a:
"depends on !PPC_OF" to Kconfig to avoid a known conflict with PPC-OF platforms
and went with the generic usb-ehci as requested.

In retro-spect I should have chosen something different, the dts files for many
existing boards already claim to be compatible with "usb-ehci", ie they have:

	compatible = "ti,ehci-omap", "usb-ehci";

In theory this should not be a problem since the "ti,ehci-omap" entry takes
presedence, but in practice using a conflicting compatible string is an issue,
because it makes which driver gets used depend on driver registration order.

This patch changes the compatible string claimed by ehci-platform to
"generic-ehci", avoiding the driver registration / module loading ordering
problems, and removes the "depends on !PPC_OF" workaround.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: jwrdegoede

Documentation/devicetree/bindings/usb/usb-ehci.txt

@@ -1,7 +1,7 @@
 USB EHCI controllers
 
 Required properties:
-  - compatible : should be "usb-ehci".
+  - compatible : should be "generic-ehci".
   - reg : should contain at least address and length of the standard EHCI
     register set for the device. Optional platform-dependent registers
     (debug-port or other) can be also specified here, but only after
@@ -27,7 +27,7 @@ Example (Sequoia 440EPx):
 
 Example (Allwinner sun4i A10 SoC):
    ehci0: usb@01c14000 {
-	   compatible = "allwinner,sun4i-a10-ehci", "usb-ehci";
+	   compatible = "allwinner,sun4i-a10-ehci", "generic-ehci";
 	   reg = <0x01c14000 0x100>;
 	   interrupts = <39>;
 	   clocks = <&ahb_gates 1>;

drivers/usb/host/Kconfig

@@ -255,7 +255,6 @@ config USB_EHCI_ATH79
 
 config USB_EHCI_HCD_PLATFORM
 	tristate "Generic EHCI driver for a platform device"
-	depends on !PPC_OF
 	default n
 	---help---
 	  Adds an EHCI host driver for a generic platform device, which

drivers/usb/host/ehci-platform.c

@@ -332,7 +332,7 @@ static int ehci_platform_resume(struct device *dev)
 static const struct of_device_id vt8500_ehci_ids[] = {
 	{ .compatible = "via,vt8500-ehci", },
 	{ .compatible = "wm,prizm-ehci", },
-	{ .compatible = "usb-ehci", },
+	{ .compatible = "generic-ehci", },
 	{}
 };
 MODULE_DEVICE_TABLE(of, vt8500_ehci_ids);