grub-efi: remove configure patch, simply seed the cache

grub-efi: remove configure patch, simply seed the cache

grub-2.00-disable-help2man patches configure.ac to disable the help2man check
because we don't need the man pages.  It also then patches configure itself so
that autogen.sh doesn't have to be called for performance reasons.  However,
do_configure causes a full autoreconf so this optimisation is moot, and can
cause patch failures when an existing build tree is re-used.

Instead, simply use CACHED_CONFIGUREVARS to tell configure that it can't find
help2man.

(From OE-Core rev: 34b9b2931da1fbf4c68a3e35f4ca56553058574b)

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