drivers/tty: ehv_bytechan fails to build as a module

ehv_bytechan is marked tristate but fails to build as a module:

drivers/tty/ehv_bytechan.c:363:1: error: type defaults to ‘int’ in declaration of ‘console_initcall’ [-Werror=implicit-int]

It doesn't make much sense for a console driver to be built as
a module, so change it to a bool.
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Scott Wood <scottwood@freescale.com>

drivers/tty/Kconfig

@@ -366,7 +366,7 @@ config TRACE_SINK
 	  "Trace data router for MIPI P1149.7 cJTAG standard".
 
 config PPC_EPAPR_HV_BYTECHAN
-	tristate "ePAPR hypervisor byte channel driver"
+	bool "ePAPR hypervisor byte channel driver"
 	depends on PPC
 	select EPAPR_PARAVIRT
 	help