memory-hotplug: create /sys/firmware/memmap entry for new memory

memory-hotplug: create /sys/firmware/memmap entry for new memory

A memmap is a directory in sysfs which includes 3 text files: start, end
and type.  For example:

start: 	0x100000
end:	0x7e7b1cff
type:	System RAM

Interface firmware_map_add was not called explicitly.  Remove it and add
function firmware_map_add_hotplug as hotplug interface of memmap.

Each memory entry has a memmap in sysfs, When we hot-add new memory, sysfs
does not export memmap entry for it.  We add a call in function add_memory
to function firmware_map_add_hotplug.

Add a new function add_sysfs_fw_map_entry() to create memmap entry, it
will be called when initialize memmap and hot-add memory.

[[email protected]: un-kernedoc a no longer kerneldoc comment]
Signed-off-by: Shaohui Zheng <[email protected]>
Acked-by: Andi Kleen <[email protected]>
Acked-by: Yasunori Goto <[email protected]>
Reviewed-by: Wu Fengguang <[email protected]>
Cc: Dave Hansen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>