usb: xhci: fix spelling mistake in Kconfig "firwmare" -> "firmware"

There are two spelling mistakes in the Kconfig text. Fix these.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20200618093224.10179-1-colin.king@canonical.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/Kconfig

@@ -44,10 +44,10 @@ config USB_XHCI_PCI
 	default y
 
 config USB_XHCI_PCI_RENESAS
-	tristate "Support for additional Renesas xHCI controller with firwmare"
+	tristate "Support for additional Renesas xHCI controller with firmware"
 	help
 	  Say 'Y' to enable the support for the Renesas xHCI controller with
-	  firwmare. Make sure you have the firwmare for the device and
+	  firmware. Make sure you have the firwmare for the device and
 	  installed on your system for this device to work.
 	  If unsure, say 'N'.