Duplicate the variables governing u-boot signing so that we can have a
different set of keys/parameters signing the SPL.
(From OE-Core rev: 0e6b0fefa02356afeb11a32dfee7f0c7c250ab7f)
Signed-off-by: Klaus Heinrich Kiwi <klaus@linux.vnet.ibm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>