xen/tmem: Remove the usage of '[no|]selfballoon' and use 'tmem.selfballooning' bool instead.

As the 'tmem' driver is the one that actually sets whether
it will use it (or not) so might as well make tmem responsible
for this knob.
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/xen/Kconfig

@@ -19,11 +19,10 @@ config XEN_SELFBALLOONING
 	  by the current usage of anonymous memory ("committed AS") and
 	  controlled by various sysfs-settable parameters.  Configuring
 	  FRONTSWAP is highly recommended; if it is not configured, self-
-	  ballooning is disabled by default but can be enabled with the
-	  'selfballooning' kernel boot parameter.  If FRONTSWAP is configured,
+	  ballooning is disabled by default. If FRONTSWAP is configured,
 	  frontswap-selfshrinking is enabled by default but can be disabled
 	  with the 'tmem.selfshrink=0' kernel boot parameter; and self-ballooning
-	  is enabled by default but can be disabled with the 'noselfballooning'
+	  is enabled by default but can be disabled with the 'tmem.selfballooning=0'
 	  kernel boot parameter.  Note that systems without a sufficiently
 	  large swap device should not enable self-ballooning.
 

drivers/xen/xen-selfballoon.c

@@ -57,9 +57,9 @@
  * configured, it is highly recommended that frontswap also be configured
  * and enabled when selfballooning is running.  So, selfballooning
  * is disabled by default if frontswap is not configured and can only
- * be enabled with the "selfballooning" kernel boot option; similarly
+ * be enabled with the "tmem.selfballooning=1" kernel boot option; similarly
  * selfballooning is enabled by default if frontswap is configured and
- * can be disabled with the "noselfballooning" kernel boot option.  Finally,
+ * can be disabled with the "tmem.selfballooning=0" kernel boot option.  Finally,
  * when frontswap is configured,frontswap-selfshrinking can be disabled
  * with the "tmem.selfshrink=0" kernel boot option.
  *
@@ -173,27 +173,6 @@ static void frontswap_selfshrink(void)
 	frontswap_shrink(tgt_frontswap_pages);
 }
 
-/* Disable with kernel boot option. */
-static bool use_selfballooning = true;
-
-static int __init xen_noselfballooning_setup(char *s)
-{
-	use_selfballooning = false;
-	return 1;
-}
-
-__setup("noselfballooning", xen_noselfballooning_setup);
-#else /* !CONFIG_FRONTSWAP */
-/* Enable with kernel boot option. */
-static bool use_selfballooning;
-
-static int __init xen_selfballooning_setup(char *s)
-{
-	use_selfballooning = true;
-	return 1;
-}
-
-__setup("selfballooning", xen_selfballooning_setup);
 #endif /* CONFIG_FRONTSWAP */
 
 #define MB2PAGES(mb)	((mb) << (20 - PAGE_SHIFT))