drm/xe: Move enable host l2 VRAM post MCR init

drm/xe: Move enable host l2 VRAM post MCR init

xe_gt_enable_host_l2_vram() is reading the XE2_GAMREQSTRM_CTRL register
that is currently missing the MCR annotation. However, just adding the
annotation doesn't work as this function is called before MCR handling
is initialized in xe_gt_mcr_init().

xe_gt_enable_host_l2_vram() is used to implement WA 16023588340 that
needs to be done as early as possible during initialization in order to
be effective since the MMIO writes impact it. In the failure scenario,
driver would simply not be able to bind successfully.

Moving xe_gt_enable_host_l2_vram() later, after MCR initialization is
done, only incurs a few additional HW accesses, particularly when
loading GuC for hwconfig. Binding/unbinding the driver 100 times in BMG
still works so it should be ok to start handling the WA a little bit
later. This is sufficient to allow adding the MCR annotation to
XE2_GAMREQSTRM_CTRL.

Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240814095614.909774-2-tejas.upadhyay@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>