Update to v5.15 kernel headers.

Kernel headers coming from:

Git: https://android.googlesource.com/kernel/common/
Branch: android-mainline
Tag: android-mainline-5.15

Test: Builds, and ran bionic unit tests on flame.
Change-Id: I86901ea6d89fb0f7384b90a47bef35d194083c24
diff --git a/libc/kernel/uapi/linux/btrfs_tree.h b/libc/kernel/uapi/linux/btrfs_tree.h
index 4e36c37..0476733 100644
--- a/libc/kernel/uapi/linux/btrfs_tree.h
+++ b/libc/kernel/uapi/linux/btrfs_tree.h
@@ -53,6 +53,8 @@
 #define BTRFS_INODE_REF_KEY 12
 #define BTRFS_INODE_EXTREF_KEY 13
 #define BTRFS_XATTR_ITEM_KEY 24
+#define BTRFS_VERITY_DESC_ITEM_KEY 36
+#define BTRFS_VERITY_MERKLE_ITEM_KEY 37
 #define BTRFS_ORPHAN_ITEM_KEY 48
 #define BTRFS_DIR_LOG_ITEM_KEY 60
 #define BTRFS_DIR_LOG_INDEX_KEY 72
@@ -424,4 +426,9 @@
   __le64 rsv_rfer;
   __le64 rsv_excl;
 } __attribute__((__packed__));
+struct btrfs_verity_descriptor_item {
+  __le64 size;
+  __le64 reserved[2];
+  __u8 encryption;
+} __attribute__((__packed__));
 #endif