drm/xe/mmio: Use single logic for waiting functions

The implementations for xe_mmio_wait32() and xe_mmio_wait32_not() are
almost identical. Let us avoid duplication of logic by having them
calling a common __xe_mmio_wait32() function.

Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240723120120.5443-2-gustavo.sousa@intel.com