drm/xe/vf: Setup VRAM based on received config data

VF drivers will obtain VRAM configuration from the GuC as part of
the VF self config. Use that configuration instead of trying to
read inaccessible registers.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240530133527.1328-6-michal.wajdeczko@intel.com

drm/xe: Promote VRAM initialization function to own file

There is no point in mixing register access and VRAM code in the
same file. Move and rename the VRAM probe function to a new file
(there are no other changes other then new simple kernel-doc).

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240530133527.1328-5-michal.wajdeczko@intel.com