mm/mmap.c: remove some redundancy in arch_get_unmapped_area_topdown()

The variable 'addr' is redundant in arch_get_unmapped_area_topdown(),
just use parameter 'addr0' directly.  Then remove the const qualifier of
the parameter, and change its name to 'addr'.

And in according with other functions, remove the const qualifier of all
other no-pointer parameters in function arch_get_unmapped_area_topdown().

Link: http://lkml.kernel.org/r/20190127041112.25599-1-nullptr.cpp@gmail.comSigned-off-by: Yang Fan <nullptr.cpp@gmail.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/mmap.c

@@ -2126,13 +2126,12 @@ arch_get_unmapped_area(struct file *filp, unsigned long addr,
  */
 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
 unsigned long
-arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
-			  const unsigned long len, const unsigned long pgoff,
-			  const unsigned long flags)
+arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
+			  unsigned long len, unsigned long pgoff,
+			  unsigned long flags)
 {
 	struct vm_area_struct *vma, *prev;
 	struct mm_struct *mm = current->mm;
-	unsigned long addr = addr0;
 	struct vm_unmapped_area_info info;
 	const unsigned long mmap_end = arch_get_mmap_end(addr);