update-rc.d: correctly look up the initscript params with overrides

update-rc.d: correctly look up the initscript params with overrides

The creation of a clone of d with extra OVERRIDES was removed in
72c1fd72d3b479c728e249eaa763116d352e945b but some of the lookups are essential
so that variables such as ${INITSCRIPT_PARAMS} get overriden and resolved
correctly on a per-package basis.

[ YOCTO #3960 ]

(From OE-Core rev: b016bc9aaabc90fe4dc98af8c5e73dfcb4526ef4)

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>