Set GS Timer to 224. Combine with Wa_1604555607 due to register FF_MODE2
not being able to be read.

V2: Math issue fixed

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Caz Yokoyama <caz.yokoyama@intel.com>
Cc: Matt Atwood <matthew.s.atwood@intel.com>
Signed-off-by: Clint Taylor <clinton.a.taylor@intel.com>
Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20200603221150.14745-1-clinton.a.taylor@intel.com