accel/amdxdna: Add zero check for pad in ioctl input structures

accel/amdxdna: Add zero check for pad in ioctl input structures

For input ioctl structures, it is better to check if the pad is zero.
Thus, the pad bytes might be usable in the future.

Suggested-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241217165446.2607585-1-lizhi.hou@amd.com