crypto: iaa - Add global_stats file and remove individual stat files

Currently, the wq_stats output also includes the global stats, while
the individual global stats are also available as separate debugfs
files.  Since these are all read-only, there's really no reason to
have them as separate files, especially since we already display them
as global stats in the wq_stats.  It makes more sense to just add a
separate global_stats file to display those, and remove them from the
wq_stats, as well as removing the individual stats files.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>