usb: xhci-renesas: Minor coding style cleanup

Change an explicit err == 0 to !err. No functional change.

Cc: Mathias Nyman <mathias.nyman@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Moritz Fischer <mdf@kernel.org>
Link: https://lore.kernel.org/r/20210718015111.389719-2-mdf@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-pci-renesas.c

@@ -595,7 +595,7 @@ int renesas_xhci_check_request_fw(struct pci_dev *pdev,
 
 	err = renesas_fw_check_running(pdev);
 	/* Continue ahead, if the firmware is already running. */
-	if (err == 0)
+	if (!err)
 		return 0;
 
 	if (err != 1)