riscv: defconfig: enable SOC_SIFIVE

Enable SOC_SIFIVE so the default upstream config is bootable on the SiFive
Unleashed Board.
And have basic support for future boards based on the same SoC.
Signed-off-by: Loys Ollivier <lollivier@baylibre.com>
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
[paul.walmsley@sifive.com: updated to apply]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

arch/riscv/configs/defconfig

@@ -14,6 +14,7 @@ CONFIG_CHECKPOINT_RESTORE=y
 CONFIG_BLK_DEV_INITRD=y
 CONFIG_EXPERT=y
 CONFIG_BPF_SYSCALL=y
+CONFIG_SOC_SIFIVE=y
 CONFIG_SMP=y
 CONFIG_MODULES=y
 CONFIG_MODULE_UNLOAD=y
@@ -51,8 +52,6 @@ CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
 CONFIG_SERIAL_OF_PLATFORM=y
 CONFIG_SERIAL_EARLYCON_RISCV_SBI=y
-CONFIG_SERIAL_SIFIVE=y
-CONFIG_SERIAL_SIFIVE_CONSOLE=y
 CONFIG_HVC_RISCV_SBI=y
 # CONFIG_PTP_1588_CLOCK is not set
 CONFIG_DRM=y
@@ -68,9 +67,6 @@ CONFIG_USB_OHCI_HCD_PLATFORM=y
 CONFIG_USB_STORAGE=y
 CONFIG_USB_UAS=y
 CONFIG_VIRTIO_MMIO=y
-CONFIG_CLK_SIFIVE=y
-CONFIG_CLK_SIFIVE_FU540_PRCI=y
-CONFIG_SIFIVE_PLIC=y
 CONFIG_SPI_SIFIVE=y
 CONFIG_EXT4_FS=y
 CONFIG_EXT4_FS_POSIX_ACL=y