configure: simpify dbus policy install dir

Using the package config to find where dbus-1 installs its config files
is needless indirection and adds a hard build-time dependency on the
dbus-1 package, which isn't necessary.  The `dbus-daemon` manpage
suggests that package-level configuration should be placed in
`/usr/share` and not `/etc`, so use `${datadir}` to place the config
files in that location.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I81ae7c2007f0a9fc7838cf287488f1c18c1a128f
1 file changed