Staging: speakup: Fix allyesconfig build on mn10300

mn10300 uses an mmio-driven uart. This is not supported by speakup, so
prevent from enabling it.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/speakup/Kconfig

 menu "Speakup console speech"
 
 config SPEAKUP
-	depends on VT
+	depends on VT && !MN10300
 	tristate "Speakup core"
 	---help---
 		This is the Speakup screen reader.  Think of it as a