NVMe: Initialize iod nents to 0
NVMe: Initialize iod nents to 0

For commands that do not map a scatter list, we need to initilaize the iod's
number of sg entries (nents) to 0 and not unmap in this case.

Signed-off-by: Keith Busch <695e2a2c1e39535baaa147c5eb4e5da14054d59f@intel.com>
Signed-off-by: Matthew Wilcox <ed1245e46949b7b8f2bca25d41520ebc8aeefcf8@intel.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas