maple_tree: remove lockdep_map_p typedef

maple_tree: remove lockdep_map_p typedef

Having the ma_external_lock field exist when CONFIG_LOCKDEP=n isn't used
anywhere, so just get rid of it.  This also avoids generating a typedef
called lockdep_map_p that could overlap with typedefs in other header
files.

Link: https://lkml.kernel.org/r/20250902-maple-lockdep-p-v1-1-3ae5a398a379@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>