Corrected retract() call for use of auto probe without sled enabled.

Hi. This patch fixes a bug I introduced whereby compiling with auto bed leveling without the z probe leaves out the retract() call. As you will see, I accidentally commented out the call during testing and forgot to correct it. Also changes the #ifdef for the sled code only to include in compile only when the sled is activated. Another oversight. Sorry. My apologies. All is well now. ;)