Move the NQN validation into the subsytem creation function, and fix the
allowed size to match the spec.
The spec is not clear about the allowed NQN size; for now, interpret it
as 223 bytes, including the null terminator (222 bytes of actual NQN
plus one terminator byte).
Change-Id: If9743ab2fe009d9d852e8b03317d9b38d8af18dc
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>