mm: includecheck fix: vmalloc.c

fix the following 'make includecheck' warning:

  mm/vmalloc.c: linux/highmem.h is included more than once.

Signed-off-by: Jaswinder Singh Rajput <jaswinderrajput@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 69511e6..2f7c9d7 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -25,7 +25,6 @@
 #include <linux/rcupdate.h>
 #include <linux/pfn.h>
 #include <linux/kmemleak.h>
-#include <linux/highmem.h>
 #include <asm/atomic.h>
 #include <asm/uaccess.h>
 #include <asm/tlbflush.h>