Previously, we used cap_lo and cap_hi to represent the 32-bit halves of
the full CAP register. However, it is simpler to keep them in a single
64-bit structure, and is no less efficient on 64-bit platforms.
Also name the NSSRS field from NVMe 1.2, which was previously reserved.
Change-Id: I1d5d9b0dccbb12373b4aed3db29c883881d43223
Signed-off-by: Daniel Verkamp <daniel.verkamp@intel.com>