x86/mm: Remove the now redundant N_MEMORY check

In commit

  f70029bb ("mm, memory_hotplug: drop CONFIG_MOVABLE_NODE")

the dependency on CONFIG_MOVABLE_NODE was removed for N_MEMORY.
Before, CONFIG_HIGHMEM && !CONFIG_MOVABLE_NODE could make (N_MEMORY ==
N_NORMAL_MEMORY) be true.

After that commit, N_MEMORY cannot be equal to N_NORMAL_MEMORY. So the
conditional check in paging_init() is not needed anymore, remove it.

 [ bp: Massage. ]
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Link: https://lkml.kernel.org/r/20200311011823.27740-1-bhe@redhat.com

arch/x86/mm/init_64.c

@@ -818,8 +818,7 @@ void __init paging_init(void)
 	 *	 will not set it back.
 	 */
 	node_clear_state(0, N_MEMORY);
-	if (N_MEMORY != N_NORMAL_MEMORY)
-		node_clear_state(0, N_NORMAL_MEMORY);
+	node_clear_state(0, N_NORMAL_MEMORY);
 
 	zone_sizes_init();
 }