i965: Don't fall back to the blitter in BlitFramebuffer

On gen4-5, we try the blitter before we even try blorp.  On newer
platforms, blorp can do everything the blitter can so there's no point
in even having the blitter fall-back path.

Reviewed-by: Topi Pohjolainen <topi.pohjolainen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/mesa/drivers/dri/i965/intel_fbo.c

@@ -915,14 +915,6 @@ intel_blit_framebuffer(struct gl_context *ctx,
       assert(!"Invalid blit");
    }
 
-   /* Try using the BLT engine. */
-   mask = intel_blit_framebuffer_with_blitter(ctx, readFb, drawFb,
-                                              srcX0, srcY0, srcX1, srcY1,
-                                              dstX0, dstY0, dstX1, dstY1,
-                                              mask);
-   if (mask == 0x0)
-      return;
-
    _swrast_BlitFramebuffer(ctx, readFb, drawFb,
                            srcX0, srcY0, srcX1, srcY1,
                            dstX0, dstY0, dstX1, dstY1,