nvme: Ignore errors when removing modules

nvme: Ignore errors when removing modules

It is no longer important for correct test functionality to
remove the modules between tests. Therefore, we ignore errors
if the modules are not removed (ie. if they are builtin).

With this patch, it is now safe to run the tests with the nvmet
modules built-in. This will be more convienent for developers
that want to run the tests in a simple VM.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>