memblock: fix kernel-doc markups

Some identifiers have different names between their prototypes
and the kernel-doc markup.

Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/f3c65f61367993a607f9daf9dc1a3bdab1f0a040.1610610937.git.mchehab+huawei@kernel.org


Signed-off-by: Jonathan Corbet <corbet@lwn.net>