vmcore: enable /proc/vmcore mmap for s390

The patch "s390/vmcore: Implement remap_oldmem_pfn_range for s390" allows
now to use mmap also on s390.

So enable mmap for s390 again.
Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Jan Willeke <willeke@de.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/vmcore.c

@@ -327,7 +327,7 @@ static inline char *alloc_elfnotes_buf(size_t notes_sz)
  * regions in the 1st kernel pointed to by PT_LOAD entries) into
  * virtually contiguous user-space in ELF layout.
  */
-#if defined(CONFIG_MMU) && !defined(CONFIG_S390)
+#ifdef CONFIG_MMU
 static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
 {
 	size_t size = vma->vm_end - vma->vm_start;