accel/amdxdna: Support submit commands without arguments

The latest userspace runtime allows generating commands which do not
have any argument. Remove the corresponding check in driver IOCTL to
enable this use case.

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://lore.kernel.org/r/20250507161500.2339701-1-lizhi.hou@amd.com
Link: https://lore.kernel.org/r/20250507161500.2339701-1-lizhi.hou@amd.com