Fix wrong script

Fix wrong script

In general, the %{buildroot} will expand to the build root as its name
suggested, this is useful at %install but not scriptlet.

And so the mistake will cause create a directory like below
/opt/home/abuild/rpmbuild/BUILDROOT/msg-service-0.9.2-4.7.i386/opt/usr/dbspace

That's not what we want and it should be /opt/usr/dbspace in fact.

Change-Id: I438fb577ad7479b97800a0056f143ae8e7d5a46e
Signed-off-by: Chengwei Yang <chengwei.yang@intel.com>