selftests: drv-net: Fix remote command checking in require_cmd()

selftests: drv-net: Fix remote command checking in require_cmd()

The require_cmd() method was checking for command availability locally
even when remote=True was specified, due to a missing host parameter.

Fix by passing host=self.remote when checking remote command
availability, ensuring commands are verified on the correct host.

Fixes: f1e68a1a4a40 ("selftests: drv-net: add require_XYZ() helpers for validating env")
Reviewed-by: Nimrod Oren <noren@nvidia.com>
Signed-off-by: Gal Pressman <gal@nvidia.com>
Link: https://patch.msgid.link/20250723135454.649342-2-gal@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>