power: load_analyzer: fix pointer-compare build warning

power: load_analyzer: fix pointer-compare build warning

Fix following pointer-compare build warning with gcc 7:
In file included from drivers/power/load_analyzer_main.c:79:0:
   drivers/power/load_analyzer_input.c: In function ‘input_rec_store_input_dev_info’:
   drivers/power/load_analyzer_input.c:32:17: warning: comparison between pointer and zero character constant [-Wpointer-compare]
      if (dev->name == '\0')
                    ^~
   drivers/power/load_analyzer_input.c:32:7: note: did you mean to dereference the pointer?
      if (dev->name == '\0')
          ^

Change-Id: I48c4028cb8ff5ddd9d23288f4d452f0eb14eb692
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>