busybox: enable swapon/off by default to make it consistent with mkswap

No size increase on busybox binary.
  Since busybox mkswap is already enabled by default it seems reasonable
  to enable swapon/off too. For ex. this obsoletes installing block-mount
  dependency for zram-swap.

Signed-off-by: Emil Muratov <gpm@hotplug.ru>
(cherry picked from commit afa5ce2493505dc0a0de4cefa9ccbf3a6389bdbc)

package/utils/busybox/Config-defaults.in

@@ -1749,16 +1749,16 @@ config BUSYBOX_DEFAULT_SETSID
 	default n
 config BUSYBOX_DEFAULT_SWAPON
 	bool
-	default n
+	default y
 config BUSYBOX_DEFAULT_FEATURE_SWAPON_DISCARD
 	bool
-	default n
+	default y
 config BUSYBOX_DEFAULT_FEATURE_SWAPON_PRI
 	bool
-	default n
+	default y
 config BUSYBOX_DEFAULT_SWAPOFF
 	bool
-	default n
+	default y
 config BUSYBOX_DEFAULT_FEATURE_SWAPONOFF_LABEL
 	bool
 	default n