batman-adv: Start new development cycle

This version will contain all the (major or even only minor) changes for
Linux 5.15.

The version number isn't a semantic version number with major and minor
information. It is just encoding the year of the expected publishing as
Linux -rc1 and the number of published versions this year (starting at 0).

Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

net/batman-adv/main.h

@@ -13,7 +13,7 @@
 #define BATADV_DRIVER_DEVICE "batman-adv"
 
 #ifndef BATADV_SOURCE_VERSION
-#define BATADV_SOURCE_VERSION "2021.2"
+#define BATADV_SOURCE_VERSION "2021.3"
 #endif
 
 /* B.A.T.M.A.N. parameters */