ARM: shmobile: defconfig: Replace USB_XHCI_RCAR by USB_XHCI_PLATFORM

USB_XHCI_RCAR is no longer enabled, as it now has a dependency on
USB_XHCI_PLATFORM, instead of selecting USB_XHCI_PLATFORM.
As the latter selects the former if ARCH_RENESAS, fix this by replacing
USB_XHCI_RCAR by USB_XHCI_PLATFORM in shmobile_defconfig.

Fixes: f879fc32 ("usb: host: xhci-rcar: Avoid long wait in xhci_reset()")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/configs/shmobile_defconfig

@@ -176,7 +176,7 @@ CONFIG_SND_SOC_AK4642=y
 CONFIG_SND_SOC_WM8978=y
 CONFIG_USB=y
 CONFIG_USB_XHCI_HCD=y
-CONFIG_USB_XHCI_RCAR=y
+CONFIG_USB_XHCI_PLATFORM=y
 CONFIG_USB_EHCI_HCD=y
 CONFIG_USB_OHCI_HCD=y
 CONFIG_USB_R8A66597_HCD=y