rpm: fix nativesdk's default var location

rpm: fix nativesdk's default var location

For now, the nativesdk-rpm's %_var in /usr/lib/rpm/macros is
'/var'. This is causing error when running `rpm -qplv A.rpm'.

   error: cannot open Packages index using db5 - Permission denied (13)
   error: cannot open Packages database in /var/lib/rpm

The rpm in SDK should be using its own database. So we should remove
this configure option, letting the SDK's native sysroot prefix to be
there in %_var. In fact, '%_usr' in macros has already got the prefix.
After this change, we have in the macros file lines like below.

"""
%_usr                   /opt/windriver/wrlinux/20.29/sysroots/x86_64-wrlinuxsdk-linux/usr
%_usrsrc                %{_usr}/src
%_var                   /opt/windriver/wrlinux/20.29/sysroots/x86_64-wrlinuxsdk-linux/var
"""

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>