Update to v6.3 kernel headers.

Kernel headers coming from:

Git: https://android.googlesource.com/kernel/common/
Branch: android-mainline
Tag: android-mainline-6.3

Test: Bionic unit tests pass.
Change-Id: I5270ef291a77343e47ef3a5fbd02b8cacf218ec5
diff --git a/libc/kernel/uapi/linux/batadv_packet.h b/libc/kernel/uapi/linux/batadv_packet.h
index ede53cf..9daed82 100644
--- a/libc/kernel/uapi/linux/batadv_packet.h
+++ b/libc/kernel/uapi/linux/batadv_packet.h
@@ -28,6 +28,7 @@
   BATADV_CODED = 0x02,
   BATADV_ELP = 0x03,
   BATADV_OGM2 = 0x04,
+  BATADV_MCAST = 0x05,
 #define BATADV_UNICAST_MIN 0x40
   BATADV_UNICAST = 0x40,
   BATADV_UNICAST_FRAG = 0x41,