NVMe: Update Identify Controller data structure

The driver was still using an old definition of Identify Controller
which only came to light once we started using the 'number of namespaces'
field properly.

Reported-by: Nisheeth Bhat <nisheeth.bhat@intel.com>
Reported-by: Khosrow Panah <Khosrow.Panah@idt.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>