accel/amdxdna: Add command doorbell and wait support

accel/amdxdna: Add command doorbell and wait support

Expose the command doorbell register to userspace on a per-hardware
context basis, enabling applications to notify the firmware of pending
commands via doorbell writes.

Introduce DRM_IOCTL_AMDXDNA_WAIT_CMD to allow userspace to wait for
completion of individual commands.

Co-developed-by: Hayden Laccabue <Hayden.Laccabue@amd.com>
Signed-off-by: Hayden Laccabue <Hayden.Laccabue@amd.com>
Signed-off-by: David Zhang <yidong.zhang@amd.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://patch.msgid.link/20260505160936.3917732-5-lizhi.hou@amd.com