RISC-V: defconfigs: Sort CONFIG_MMC

This should have no functional change, it just sorts CONFIG_MMC the same
way savedefconfig does.  This only touches the rv64 defconfig because
rv32_defconfig was already sorted correctly.
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

arch/riscv/configs/defconfig

@@ -88,10 +88,10 @@ CONFIG_USB_OHCI_HCD=y
 CONFIG_USB_OHCI_HCD_PLATFORM=y
 CONFIG_USB_STORAGE=y
 CONFIG_USB_UAS=y
+CONFIG_MMC=y
 CONFIG_MMC_SDHCI=y
 CONFIG_MMC_SDHCI_PLTFM=y
 CONFIG_MMC_SDHCI_CADENCE=y
-CONFIG_MMC=y
 CONFIG_MMC_SPI=y
 CONFIG_RTC_CLASS=y
 CONFIG_VIRTIO_PCI=y