um: 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 <[email protected]>
Acked-by: Anton Ivanov <[email protected]>
Signed-off-by: Richard Weinberger <[email protected]>

Author: krzk

arch/um/Kconfig

@@ -153,7 +153,7 @@ config KERNEL_STACK_ORDER
 	  It is possible to reduce the stack to 1 for 64BIT and 0 for 32BIT on
 	  older (pre-2017) CPUs. It is not recommended on newer CPUs due to the
 	  increase in the size of the state which needs to be saved when handling
-          signals.
+	  signals.
 
 config MMAPPER
 	tristate "iomem emulation driver"