drm/i915: move i915_gem_object_needs_bit17_swizzle() to i915_gem_tiling.[ch]

Move i915_gem_object_needs_bit17_swizzle() to i915_gem_tiling.[ch] as a
i915_gem_object function related to tiling. Also un-inline while at it;
does not seem like this is a function needed in hot paths.

v2: i915_gem_tiling.[ch] instead of intel_ggtt_fencing.[ch] (Chris)

Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220316095018.137998-1-jani.nikula@intel.com