x86: fix efi.lds dependency generation

x86: fix efi.lds dependency generation

RANDCONFIG builds discover efi.lds is not updated when autogenerated
headers are updated.

Upon inspection, the generated .d file contains xen.lds.o as target,
not the once thought efi.lds.o. That's because gcc disregards the
output object name specified by -o when generating dependency, so the
sed invocation has no effect.

Arguably that's a bug in gcc, which can be fixed at some point, so we
make the sed rune work with *.lds. At the same time replace the
hardcoded sed rune for xen.lds with the new one.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>