riscv: Fix Kconfig indentation

Adjust indentation from spaces to tab (+optional two spaces) as in
coding style with command like:
	$ sed -e 's/^        /\t/' -i */Kconfig
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
[paul.walmsley@sifive.com: use two leading spaces for help text to align
 with common arch/ practice]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>

arch/riscv/Kconfig.socs

 menu "SoC selection"
 
 config SOC_SIFIVE
-       bool "SiFive SoCs"
-       select SERIAL_SIFIVE
-       select SERIAL_SIFIVE_CONSOLE
-       select CLK_SIFIVE
-       select CLK_SIFIVE_FU540_PRCI
-       select SIFIVE_PLIC
-       help
-         This enables support for SiFive SoC platform hardware.
+	bool "SiFive SoCs"
+	select SERIAL_SIFIVE
+	select SERIAL_SIFIVE_CONSOLE
+	select CLK_SIFIVE
+	select CLK_SIFIVE_FU540_PRCI
+	select SIFIVE_PLIC
+	help
+	  This enables support for SiFive SoC platform hardware.
 
 endmenu