drm/i915: remove intel_gvt_gtt::{mm_alloc_page_table, mm_free_page_table}

drm/i915: remove intel_gvt_gtt::{mm_alloc_page_table, mm_free_page_table}

intel_gvt_gtt::{mm_alloc_page_table,mm_free_page_table} are not used
since commit ede9d0cfcb78 (drm/i915/gvt: Rework shadow graphic memory
management code). Drop them.

Found by https://github.com/jirislaby/clang-struct.

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: intel-gfx@lists.freedesktop.org
Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240216065326.6910-5-jirislaby@kernel.org