health-check: Ignoring HP hidden disks

detect.py reports Internal disks from HP's controllers while they are
not reacheable directly from Linux. So let's ignore thoses devices while
running the storage test.
health-check: s/iops/IOps/

This very simple change insure consistency with KBps.

Before:
('disk', 'sdb', 'standalone_randread_4k_KBps', 6227),
('disk', 'sdb', 'standalone_randread_4k_iops', '1553 '),

After:
('disk', 'sdb', 'standalone_randread_4k_KBps', 6227),
('disk', 'sdb', 'standalone_randread_4k_IOps', '1553 '),