nvme.ko: Don't include nvme_util.c

[jhb]

Summary

This file is already included in cam.ko which is nvme.ko depends on
unconditionally.

Sponsored by: Chelsio Communications

[jhb]

I've tested this with numerous kernels combinations:

• kernel without CAM but with nvme + nvd
• kernel without nvme (MINIMAL was too big) but with CAM, nvme.ko can be kldloaded and works
• kernel without CAM or nvme, nvme.ko can be kldloaded and pulls in cam.ko as an automatic dependency and works