kbuild, deb-pkg: fix install scripts for posix sh

bash versus dash and posh disagree on expanding $@ within double quotes:
export x="$@"
see http://bugs.debian.org/381091 for details
just use the arglist with $*.

dpkg: error processing linux-image-2.6.31-rc1_2.6.31-rc1-18_i386.deb (--install):
 subprocess pre-installation script returned error exit status 2
export: 6: 2.6.31-rc1-18: bad variable name
fixes http://bugzilla.kernel.org/show_bug.cgi?id=13567

seen on Ubuntu as there dash is the default sh,
versus bash on Debian.

Reported-by: Pauli <suokkos@gmail.com>
Cc: Frans Pop <elendil@planet.nl>
Signed-off-by: maximilian attems <max@stro.at>
Acked-By: Andres Salomon <dilinger@collabora.co.uk>