i965: compile driver source as convenience library

i965: compile driver source as convenience library

Compile driver source into a noinst convenience library and
link it into the driver module.  This allows for tests to link
to the driver library, too, for testing.

Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>
Reviewed-by: Sean V Kelley <seanvk@posteo.de>
(cherry picked from commit b133e7c43f3ad7d346000bb69dbafc5f925dabe6)