drm/i915: replace select with dependency for visible DEBUG_OBJECTS

drm/i915: replace select with dependency for visible DEBUG_OBJECTS

DRM_I915_SW_FENCE_DEBUG_OBJECTS currently selects DEBUG_OBJECTS even though
DEBUG_OBJECTS is visible to users. Other config options use 'depends on'
for DEBUG_OBJECTS, so let's do the same here.

This select-visible Kconfig misusage was detected by Kconfirm, a static
analysis tool for Kconfig.

Signed-off-by: Julian Braha <julianbraha@gmail.com>
Link: https://patch.msgid.link/20260502191932.4491-1-julianbraha@gmail.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>