xhci: fix incorrect type in assignment in xhci_count_num_dropped_endpoints()

The fields 'add_flags' and 'drop_flags' in struct xhci_input_control_ctx
have type __le32 and need to be converted to CPU byteorder before being
used to derive the number of dropped endpoints.
This bug was found using sparse.

This patch is not suitable for stable, since the bug would only be
triggered on big endian systems, and the code only runs for Intel xHCI
host controllers, which are always integrated into little endian
systems.
Signed-off-by: NXenia Ragiadakou <burzalodowa@gmail.com>
Signed-off-by: NSarah Sharp <sarah.a.sharp@linux.intel.com>

drivers/usb/host/xhci.c

@@ -1909,8 +1909,8 @@ static unsigned int xhci_count_num_dropped_endpoints(struct xhci_hcd *xhci,
 	u32 valid_add_flags;
 	u32 valid_drop_flags;
 
-	valid_add_flags = ctrl_ctx->add_flags >> 2;
-	valid_drop_flags = ctrl_ctx->drop_flags >> 2;
+	valid_add_flags = le32_to_cpu(ctrl_ctx->add_flags) >> 2;
+	valid_drop_flags = le32_to_cpu(ctrl_ctx->drop_flags) >> 2;
 
 	return hweight32(valid_drop_flags) -
 		hweight32(valid_add_flags & valid_drop_flags);