mm: page_alloc: Add debug log in free_reserved_area for static memory

For INITRD and initmem memory is reserved through "memblock_reserve"
during boot up but it is free via "free_reserved_area" instead
of "memblock_free".
For example:
[    0.294848] Freeing initrd memory: 12K.
[    0.696688] Freeing unused kernel memory: 4096K.

To get the start and end address of the above freed memory and to account
proper memblock added memblock_dbg log in "free_reserved_area".
After adding log:
[    0.294837] memblock_free: [0x00000083600000-0x00000083603000] free_initrd_mem+0x20/0x28
[    0.294848] Freeing initrd memory: 12K.
[    0.695246] memblock_free: [0x00000081600000-0x00000081a00000] free_initmem+0x70/0xc8
[    0.696688] Freeing unused kernel memory: 4096K.

Change-Id: I5ebbb9c1ced481e0ce2acd839e85526aa8dadf75
Signed-off-by: Faiyaz Mohammed <faiyazm@codeaurora.org>

mm/page_alloc.c

@@ -6836,6 +6836,11 @@ unsigned long free_reserved_area(void *start, void *end, int poison, char *s)
 		pr_info("Freeing %s memory: %ldK\n",
 			s, pages << (PAGE_SHIFT - 10));
 
+#ifdef CONFIG_HAVE_MEMBLOCK
+		memblock_dbg("memblock_free: [%#016llx-%#016llx] %pF\n",
+			__pa(start), __pa(end), (void *)_RET_IP_);
+#endif
+
 	return pages;
 }
 EXPORT_SYMBOL(free_reserved_area);