r8169: add missing conditional compiling for call to r8169_remove_leds

Add missing dependency on CONFIG_R8169_LEDS. As-is a link error occurs
if config option CONFIG_R8169_LEDS isn't enabled.

Fixes: 19fa4f2a

 ("r8169: fix LED-related deadlock on module removal")
Reported-by: Venkat Rao Bagalkote <venkat88@linux.vnet.ibm.com>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Tested-By: Venkat Rao Bagalkote <venkat88@linux.vnet.ibm.com>
Link: https://lore.kernel.org/r/d080038c-eb6b-45ac-9237-b8c1cdd7870f@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>