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/magic.h b/libc/kernel/uapi/linux/magic.h
index 38b5c85..ebbb58c 100644
--- a/libc/kernel/uapi/linux/magic.h
+++ b/libc/kernel/uapi/linux/magic.h
@@ -35,6 +35,7 @@
 #define SQUASHFS_MAGIC 0x73717368
 #define ECRYPTFS_SUPER_MAGIC 0xf15f
 #define EFS_SUPER_MAGIC 0x414A53
+#define EROFS_SUPER_MAGIC_V1 0xE0F5E1E2
 #define EXT2_SUPER_MAGIC 0xEF53
 #define EXT3_SUPER_MAGIC 0xEF53
 #define XENFS_SUPER_MAGIC 0xabba1974
@@ -67,6 +68,7 @@
 #define REISERFS_SUPER_MAGIC_STRING "ReIsErFs"
 #define REISER2FS_SUPER_MAGIC_STRING "ReIsEr2Fs"
 #define REISER2FS_JR_SUPER_MAGIC_STRING "ReIsEr3Fs"
+#define SDCARDFS_SUPER_MAGIC 0x5dca2df5
 #define SMB_SUPER_MAGIC 0x517B
 #define CGROUP_SUPER_MAGIC 0x27e0eb
 #define CGROUP2_SUPER_MAGIC 0x63677270