scripts/package: 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