dell-laptop: remove duplicate Kconfig entry under drivers/misc

This showed up as an unselectable option when using xconfig and
searching for "dell".  It must been overlooked when dell-laptop
was moved to drivers/platform/x86.

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Signed-off-by: Len Brown <len.brown@intel.com>