drm/i915: Generate i915_params {} using a macro

drm/i915: Generate i915_params {} using a macro

I want to print the struct from the error state and so would like to use
the existing struct definition as the template ala DEV_INFO*

v2: Use MEMBER() rather than p().

Signed-off-by: Chris Wilson <[email protected]>
Reviewed-by: Joonas Lahtinen <[email protected]>
Acked-by: Jani Nikula <[email protected]>
Acked-by: Daniel Vetter <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]