drm/i915/guc: Correctly free guc capture struct on error

On error the "new" allocation is not freed, so add the required kfree.

Fixes: 247f8071 ("drm/i915/guc: Pre-allocate output nodes for extraction")
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Alan Previn <alan.previn.teres.alexis@intel.com>
Cc: John Harrison <john.c.harrison@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220324000439.2370440-1-daniele.ceraolospurio@intel.com