arm64: defconfig: Enable usb2_clksel for R-Car Gen3 and RZ/G2

There is a clock driver that's needed when using an external
USB reference clock called usb2_clksel.
Enable it in the defconfig.
Signed-off-by: Adam Ford <aford173@gmail.com>
Link: https://lore.kernel.org/r/20210513114617.30191-3-aford173@gmail.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

arch/arm64/configs/defconfig

@@ -987,6 +987,7 @@ CONFIG_SM_GPUCC_8250=y
 CONFIG_SM_DISPCC_8250=y
 CONFIG_QCOM_HFPLL=y
 CONFIG_CLK_GFM_LPASS_SM8250=m
+CONFIG_CLK_RCAR_USB2_CLOCK_SEL=y
 CONFIG_HWSPINLOCK=y
 CONFIG_HWSPINLOCK_QCOM=y
 CONFIG_ARM_MHU=y