USB: xhci: Remove buggy assignment in next_trb()

The code to increment the TRB pointer has a slight ambiguity that could
lead to a bug on different compilers.  The ANSI C specification does not
specify the precedence of the assignment operator over the postfix
operator.  gcc 4.4 produced the correct code (increment the pointer and
assign the value), but a MIPS compiler that one of John's clients used
assigned the old (unincremented) value.

Remove the unnecessary assignment to make all compilers produce the
correct assembly.
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/xhci-ring.c

@@ -131,7 +131,7 @@ static void next_trb(struct xhci_hcd *xhci,
 		*seg = (*seg)->next;
 		*trb = ((*seg)->trbs);
 	} else {
-		*trb = (*trb)++;
+		(*trb)++;
 	}
 }