drm/ttm: Fix incorrect use of kernel-doc format

drm/ttm: Fix incorrect use of kernel-doc format

Add a missing colon.

Cc: dri-devel@lists.freedesktop.org
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/linux-next/20241010160942.192caf60@canb.auug.org.au/
Fixes: fc5d96670eb2 ("drm/ttm: Move swapped objects off the manager's LRU list")
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241010124545.82023-1-thomas.hellstrom@linux.intel.com