powerpc/mpc5200: fix bestcomm Kconfig dependencies

Without this patch it is possible to select drivers which require
bestcomm support without bestcomm support being selected.  This
patch reworks the bestcomm dependencies to ensure the correct
bestcomm tasks are always enabled.

Reported-by: Hans Lehmann <hans.lehmann@ritter-elektronik.de>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
diff --git a/arch/powerpc/sysdev/bestcomm/Kconfig b/arch/powerpc/sysdev/bestcomm/Kconfig
index 57cc565..0b192a1 100644
--- a/arch/powerpc/sysdev/bestcomm/Kconfig
+++ b/arch/powerpc/sysdev/bestcomm/Kconfig
@@ -17,23 +17,20 @@
 	  answer Y or M. Otherwise say N.
 
 config PPC_BESTCOMM_ATA
-	tristate "Bestcomm ATA task support"
+	tristate
 	depends on PPC_BESTCOMM
-	default n
 	help
 	  This option enables the support for the ATA task.
 
 config PPC_BESTCOMM_FEC
-	tristate "Bestcomm FEC tasks support"
+	tristate
 	depends on PPC_BESTCOMM
-	default n
 	help
 	  This option enables the support for the FEC tasks.
 
 config PPC_BESTCOMM_GEN_BD
-	tristate "Bestcomm GenBD tasks support"
+	tristate
 	depends on PPC_BESTCOMM
-	default n
 	help
 	  This option enables the support for the GenBD tasks.