lmsensors: reset RDEPENDS_${PN}-dev for lmsensors and lmsensors-config

When building with dev-pkgs enabled I was hitting an error lmsensors
not available. Resetting the RDEPENDS for the dev packages fixes this
error as there is no lmsensors or lmsensors-config package defined.

Signed-off-by: Jack Mitchell <jmitchell@cbnl.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>