Update to v5.10 kernel headers.

Kernel headers coming from:

Git: https://android.googlesource.com/kernel/common/
Branch: android-mainline
Tag: android-mainline-5.10

Test: Built cuttlefish and flame images. Ran bionic unit tests on both.
Change-Id: I37ffc850970adcce1febbe2269c202632fce763a
diff --git a/libc/kernel/uapi/linux/l2tp.h b/libc/kernel/uapi/linux/l2tp.h
index 3f77b25..c65f7a9 100644
--- a/libc/kernel/uapi/linux/l2tp.h
+++ b/libc/kernel/uapi/linux/l2tp.h
@@ -103,6 +103,7 @@
   L2TP_ATTR_RX_OOS_PACKETS,
   L2TP_ATTR_RX_ERRORS,
   L2TP_ATTR_STATS_PAD,
+  L2TP_ATTR_RX_COOKIE_DISCARDS,
   __L2TP_ATTR_STATS_MAX,
 };
 #define L2TP_ATTR_STATS_MAX (__L2TP_ATTR_STATS_MAX - 1)