um: remove used STDIO_CONSOLE Kconfig param

This removes the STDIO_CONSOLE Kconfig parameter which
is defined but no longer used anywhere in the makefiles and source code.

Signed-off-by: Michael Opdenacker <[e-mail]>
Signed-off-by: Richard Weinberger <[e-mail]>

arch/um/Kconfig.char

···
 	help
 	  console driver which dumps all printk messages to stderr.
 
-config STDIO_CONSOLE
-	bool
-	default y
-
 config SSL
 	bool "Virtual serial line"
 	help