drm/amd: Add missing kdoc for amd_ip_funcs complete callback

The `complete` callback should be described in kernel doc.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/linux-next/20250619205931.41cf9332@canb.auug.org.au/
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://lore.kernel.org/r/20250620041420.3585005-1-superm1@kernel.org
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Author: superm1

drivers/gpu/drm/amd/include/amd_shared.h

@@ -396,6 +396,7 @@ enum amd_dpm_forced_level;
  *                   (such as allocating any required memory)
  * @suspend: handles IP specific hw/sw changes for suspend
  * @resume: handles IP specific hw/sw changes for resume
+ * @complete: handles IP specific changes after resume
  * @is_idle: returns current IP block idle status
  * @wait_for_idle: poll for idle
  * @check_soft_reset: check soft reset the IP block