scripts/package/Makefile: KBUILD_OUTPUT is useless in rpm build

[Bin Wang <wbin00@gmail.com>]

I found KBUILD_OUTPUT variable is useless in the rpm-pkg and rpm target.

Yes there is a comment said:

# Note that the rpm-pkg target cannot be used with KBUILD_OUTPUT,
# but the binrpm-pkg target can; for some reason O= gets ignored.

It does not say for what reason. Also, the code under rpm-pkg checks if
KBUILD_OUTPUT is defined.

> @if test -n "$(KBUILD_OUTPUT)"; then \
> echo "Building source + binary RPM is not possible outside the"; \
> echo "kernel source tree. Don't set KBUILD_OUTPUT, or use the"; \
> echo "binrpm-pkg target instead."; \
> false; \
> fi

But the fact is, whether or not the user use "O=" option, KBUILD_OUTPUT
is always empty. I try to figure out why but the big Makefile drives me
crazy. I'm thinking if the "O=" option really don't effect KBUILD_OUTPUT
here, at least remove these code.

-- 
Bin Wang