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 <[e-mail]>
Acked-by: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Scott Wood <[e-mail]>

drivers/tty/Kconfig

···
 	  "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