drm/i915/gen9: Add WaFbcWakeMemOn

drm/i915/gen9: Add WaFbcWakeMemOn

Set bit 8 in 0x43224 to prevent screen corruption and system
hangs on high memory bandwidth conditions. The same wa also suggest
setting bit 31 on ARB_CTL. According to another workaround we gain
better idle power savings when FBC is enabled.

v2: use correct workaround name
v3: split out overlapping wa for corruption avoidance (Ville)

References: HSD#2137218, HSD#2227171, HSD#2136579, BSID#883
Cc: Paulo Zanoni <[email protected]>
Cc: Ville Syrjälä <[email protected]>
Signed-off-by: Mika Kuoppala <[email protected]>
Reviewed-by: Ville Syrjälä <[email protected]>
Link: http://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit 303d4ea522e8672a1b62d968a5b6764929adc292)
Signed-off-by: Mika Kuoppala <[email protected]>