usb: renesas: Fix R-Car spelling

The correct spelling is R-Car, including the dash, update the usage.
Kconfig strings and comment changes only, no functional change.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
diff --git a/drivers/usb/host/xhci-rcar.c b/drivers/usb/host/xhci-rcar.c
index 38c5928..b728070 100644
--- a/drivers/usb/host/xhci-rcar.c
+++ b/drivers/usb/host/xhci-rcar.c
@@ -2,7 +2,7 @@
 /*
  * Copyright (C) 2017 Marek Vasut <marek.vasut@gmail.com>
  *
- * Renesas RCar USB HOST xHCI Controller
+ * Renesas R-Car USB HOST xHCI Controller
  */
 
 #include <clk.h>