make sure init_mm is included

mm/sparse-vmemmap.c uses init_mm in some places. However, it is not present in any of the headers currently included in the file.

init_mm is defined as extern in sched.h, so we add it to the headers list

Up to now, this problem was masked by the fact that functions like set_pte_at() and pmd_populate_kernel() are usually macros that expand to simpler variants that does not use the first parameter at all.

---
 mm/sparse-vmemmap.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

index d3b718b..22620f6 100644
@@ -24,6 +24,7 @@
 #include <linux/module.h>
 #include <linux/spinlock.h>
 #include <linux/vmalloc.h>
+#include <linux/sched.h>
 #include <asm/dma.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>

1.4.4.2