drivers: base/node.c: fixes a kernel-doc markups

There was a typo at the name of the vars inside the kernel-doc
comment, causing those warnings:

	./drivers/base/node.c:690: warning: Function parameter or member 'mem_nid' not described in 'register_memory_node_under_compute_node'
	./drivers/base/node.c:690: warning: Function parameter or member 'cpu_nid' not described in 'register_memory_node_under_compute_node'
	./drivers/base/node.c:690: warning: Excess function parameter 'mem_node' description in 'register_memory_node_under_compute_node'
	./drivers/base/node.c:690: warning: Excess function parameter 'cpu_node' description in 'register_memory_node_under_compute_node'

There's also a description missing here:
	./drivers/base/node.c:78: warning: Function parameter or member 'hmem_attrs' not described in 'node_access_nodes'

Copy an existing description from another function call.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>