Improve error messages where possible.
Also change return code values to negative in bdev_pmem.c so that
it follows the same pattern as other bdev modules.
Change-Id: I81b205a41104e15457154d1e31540210636ef9d3
Signed-off-by: Karol Latecki <karol.latecki@intel.com>
Reviewed-on: https://review.gerrithub.io/c/spdk/spdk/+/461548
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Vitaliy Mysak <vitaliy.mysak@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
5f96e92c8c