drm/i915: remove unused GEM_DEBUG_DECL() and GEM_DEBUG_BUG_ON()

There are already too many choices here, take away the unused ones.

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/20220504183716.987793-1-jani.nikula@intel.com

drivers/gpu/drm/i915/i915_gem.h

@@ -54,9 +54,7 @@ struct drm_i915_private;
 	} while(0)
 #define GEM_WARN_ON(expr) WARN_ON(expr)
 
-#define GEM_DEBUG_DECL(var) var
 #define GEM_DEBUG_EXEC(expr) expr
-#define GEM_DEBUG_BUG_ON(expr) GEM_BUG_ON(expr)
 #define GEM_DEBUG_WARN_ON(expr) GEM_WARN_ON(expr)
 
 #else
@@ -66,9 +64,7 @@ struct drm_i915_private;
 #define GEM_BUG_ON(expr) BUILD_BUG_ON_INVALID(expr)
 #define GEM_WARN_ON(expr) ({ unlikely(!!(expr)); })
 
-#define GEM_DEBUG_DECL(var)
 #define GEM_DEBUG_EXEC(expr) do { } while (0)
-#define GEM_DEBUG_BUG_ON(expr)
 #define GEM_DEBUG_WARN_ON(expr) ({ BUILD_BUG_ON_INVALID(expr); 0; })
 #endif