drivers/firmware/memmap.c: pass the correct argument to firmware_map_find_entry_bootmem()
firmware_map_add_hotplug() calls firmware_map_find_entry_bootmem() to
get free firmware_map_entry. But end arguments is not correct. So
firmware_map_find_entry_bootmem() cannot not find firmware_map_entry.
The patch passes the correct end argument to firmware_map_find_entry_bootmem().