USB: EHCI: fix build error in ehci-mxc

This patch (as1643b) fixes a build error in ehci-hcd when compiling for
ARM with allmodconfig:

drivers/usb/host/ehci-hcd.c:1285:0: warning: "PLATFORM_DRIVER" redefined [enabled by default]
drivers/usb/host/ehci-hcd.c:1255:0: note: this is the location of the previous definition
drivers/usb/host/ehci-mxc.c:280:31: warning: 'ehci_mxc_driver' defined but not used [-Wunused-variable]
drivers/usb/host/ehci-hcd.c:1285:0: warning: "PLATFORM_DRIVER" redefined [enabled by default]
drivers/usb/host/ehci-hcd.c:1255:0: note: this is the location of the previous definition

The fix is to convert ehci-mxc over to the new "ehci-hcd is a library"
scheme so that it can coexist peacefully with the ehci-platform
driver.  As part of the conversion the ehci_mxc_priv data structure,
which was allocated dynamically, is now placed where it belongs: in
the private area at the end of struct ehci_hcd.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index d09ff8f..09537b2 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -1246,11 +1246,6 @@
 #define	PLATFORM_DRIVER		ehci_fsl_driver
 #endif
 
-#ifdef CONFIG_USB_EHCI_MXC
-#include "ehci-mxc.c"
-#define PLATFORM_DRIVER		ehci_mxc_driver
-#endif
-
 #ifdef CONFIG_USB_EHCI_SH
 #include "ehci-sh.c"
 #define PLATFORM_DRIVER		ehci_hcd_sh_driver
@@ -1349,6 +1344,7 @@
 #if !IS_ENABLED(CONFIG_USB_EHCI_PCI) && \
 	!IS_ENABLED(CONFIG_USB_EHCI_HCD_PLATFORM) && \
 	!IS_ENABLED(CONFIG_USB_CHIPIDEA_HOST) && \
+	!IS_ENABLED(CONFIG_USB_EHCI_MXC) && \
 	!defined(PLATFORM_DRIVER) && \
 	!defined(PS3_SYSTEM_BUS_DRIVER) && \
 	!defined(OF_PLATFORM_DRIVER) && \