USB: EHCI: declare hostpc register as zero-length array

commit 7e8b3dfe upstream.

The HOSTPC extension registers found in some EHCI implementations form
a variable-length array, with one element for each port.  Therefore
the hostpc field in struct ehci_regs should be declared as a
zero-length array, not a single-element array.

This fixes a problem reported by UBSAN.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: Wilfried Klaebe <linux-kernel@lebenslange-mailadresse.de>
Tested-by: Wilfried Klaebe <linux-kernel@lebenslange-mailadresse.de>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>

include/linux/usb/ehci_def.h

@@ -178,11 +178,11 @@ struct ehci_regs {
  * PORTSCx
  */
 	/* HOSTPC: offset 0x84 */
-	u32		hostpc[1];	/* HOSTPC extension */
+	u32		hostpc[0];	/* HOSTPC extension */
 #define HOSTPC_PHCD	(1<<22)		/* Phy clock disable */
 #define HOSTPC_PSPD	(3<<25)		/* Port speed detection */
 
-	u32		reserved5[16];
+	u32		reserved5[17];
 
 	/* USBMODE_EX: offset 0xc8 */
 	u32		usbmode_ex;	/* USB Device mode extension */