Update to android-mainline kernel headers v5.4.

Update generate_uapi_headers.sh to checkout the android mainline
kernel. Also, add a small modification to look for the kernel directory
in common not linux-stable.

Remove deprecated android headers from android/uapi/linux. Also,
remove f_accessory.h since it's in the android mainline kernel.

Test: Builds and runs on walleye.
Change-Id: Ia371305e19f56e6bcc2db6d5b4d299819f07ffc6
diff --git a/libc/kernel/uapi/linux/net_dropmon.h b/libc/kernel/uapi/linux/net_dropmon.h
index ec7f4ec..a3d9119 100644
--- a/libc/kernel/uapi/linux/net_dropmon.h
+++ b/libc/kernel/uapi/linux/net_dropmon.h
@@ -54,8 +54,58 @@
   NET_DM_CMD_CONFIG,
   NET_DM_CMD_START,
   NET_DM_CMD_STOP,
+  NET_DM_CMD_PACKET_ALERT,
+  NET_DM_CMD_CONFIG_GET,
+  NET_DM_CMD_CONFIG_NEW,
+  NET_DM_CMD_STATS_GET,
+  NET_DM_CMD_STATS_NEW,
   _NET_DM_CMD_MAX,
 };
 #define NET_DM_CMD_MAX (_NET_DM_CMD_MAX - 1)
 #define NET_DM_GRP_ALERT 1
+enum net_dm_attr {
+  NET_DM_ATTR_UNSPEC,
+  NET_DM_ATTR_ALERT_MODE,
+  NET_DM_ATTR_PC,
+  NET_DM_ATTR_SYMBOL,
+  NET_DM_ATTR_IN_PORT,
+  NET_DM_ATTR_TIMESTAMP,
+  NET_DM_ATTR_PROTO,
+  NET_DM_ATTR_PAYLOAD,
+  NET_DM_ATTR_PAD,
+  NET_DM_ATTR_TRUNC_LEN,
+  NET_DM_ATTR_ORIG_LEN,
+  NET_DM_ATTR_QUEUE_LEN,
+  NET_DM_ATTR_STATS,
+  NET_DM_ATTR_HW_STATS,
+  NET_DM_ATTR_ORIGIN,
+  NET_DM_ATTR_HW_TRAP_GROUP_NAME,
+  NET_DM_ATTR_HW_TRAP_NAME,
+  NET_DM_ATTR_HW_ENTRIES,
+  NET_DM_ATTR_HW_ENTRY,
+  NET_DM_ATTR_HW_TRAP_COUNT,
+  NET_DM_ATTR_SW_DROPS,
+  NET_DM_ATTR_HW_DROPS,
+  __NET_DM_ATTR_MAX,
+  NET_DM_ATTR_MAX = __NET_DM_ATTR_MAX - 1
+};
+enum net_dm_alert_mode {
+  NET_DM_ALERT_MODE_SUMMARY,
+  NET_DM_ALERT_MODE_PACKET,
+};
+enum {
+  NET_DM_ATTR_PORT_NETDEV_IFINDEX,
+  NET_DM_ATTR_PORT_NETDEV_NAME,
+  __NET_DM_ATTR_PORT_MAX,
+  NET_DM_ATTR_PORT_MAX = __NET_DM_ATTR_PORT_MAX - 1
+};
+enum {
+  NET_DM_ATTR_STATS_DROPPED,
+  __NET_DM_ATTR_STATS_MAX,
+  NET_DM_ATTR_STATS_MAX = __NET_DM_ATTR_STATS_MAX - 1
+};
+enum net_dm_origin {
+  NET_DM_ORIGIN_SW,
+  NET_DM_ORIGIN_HW,
+};
 #endif