firmware/memmap: avoid type conflicts with the generic memmap_init()

Fix this build error:

  drivers/firmware/memmap.c:240:19: error: conflicting types for 'memmap_init'
  arch/ia64/include/asm/pgtable.h:565:17: note: previous declaration of 'memmap_init' was here
Signed-off-by: NFengguang Wu <fengguang.wu@intel.com>
Cc: Bernhard Walle <bwalle@suse.de>
Cc: Glauber Costa <glommer@parallels.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/firmware/memmap.c

@@ -237,7 +237,7 @@ static ssize_t memmap_attr_show(struct kobject *kobj,
  * firmware_map_add() or firmware_map_add_early() afterwards, the entries
  * are not added to sysfs.
  */
-static int __init memmap_init(void)
+static int __init firmware_memmap_init(void)
 {
 	struct firmware_map_entry *entry;
 
@@ -246,5 +246,5 @@ static int __init memmap_init(void)
 
 	return 0;
 }
-late_initcall(memmap_init);
+late_initcall(firmware_memmap_init);