x86/numa_emulation: Assign physnode_mask directly from numa_nodes_parsed

x86/numa_emulation: Assign physnode_mask directly from numa_nodes_parsed

numa_init() has already called init_func(), which is responsible for
setting numa_nodes_parsed, so use this nodemask instead of re-finding it
when calling numa_emulation().

This patch gets the physnode_mask directly from numa_nodes_parsed. At
the same time, it corrects the comment of these two functions.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: bp@alien8.de
Cc: kirill@shutemov.name
Cc: tj@kernel.org
Link: http://lkml.kernel.org/r/20170708013059.29708-3-richard.weiyang@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>