um: Cleanup mem_32/64.c headers

Include only headers we really need.

Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/arch/x86/um/mem_32.c b/arch/x86/um/mem_32.c
index f40281e..744afdc 100644
--- a/arch/x86/um/mem_32.c
+++ b/arch/x86/um/mem_32.c
@@ -7,8 +7,7 @@
  */
 
 #include <linux/mm.h>
-#include <asm/page.h>
-#include <asm/mman.h>
+#include <asm/elf.h>
 
 static struct vm_area_struct gate_vma;