numa: fix NUMA compile error when sysfs and procfs are disabled

The vmstat_text array is only defined for CONFIG_SYSFS or CONFIG_PROC_FS,
yet it is referenced for per-node vmstat with CONFIG_NUMA:

drivers/built-in.o: In function `node_read_vmstat':
node.c:(.text+0x1106df): undefined reference to `vmstat_text'

Introduced in commit fa25c503dfa2 ("mm: per-node vmstat: show proper
vmstats").

Define the array for CONFIG_NUMA as well.

[[e-mail]: remove unneeded ifdefs]
Signed-off-by: David Rientjes <[e-mail]>
Reported-by: Cong Wang <[e-mail]>
Acked-by: Randy Dunlap <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

mm/vmstat.c

···
 }
 #endif
 
-#if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS)
+#if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || defined(CONFIG_NUMA)
 #ifdef CONFIG_ZONE_DMA
 #define TEXT_FOR_DMA(xx) xx "_dma",
 #else
···
 
 #endif /* CONFIG_VM_EVENTS_COUNTERS */
 };
-#endif /* CONFIG_PROC_FS || CONFIG_SYSFS */
+#endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
 
 
 #ifdef CONFIG_PROC_FS