i915g: Allow use of I915_DEBUG= options on non-DEBUG builds.

All the checks should be cheap, no need making things harder to debug.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11617>

src/gallium/drivers/i915/i915_debug.h

@@ -47,7 +47,6 @@ struct i915_winsys_batchbuffer;
 
 extern unsigned i915_debug;
 
-#ifdef DEBUG
 static inline bool
 I915_DBG_ON(unsigned flags)
 {
@@ -65,13 +64,6 @@ I915_DBG(unsigned flags, const char *fmt, ...)
       va_end(args);
    }
 }
-#else
-#define I915_DBG_ON(flags) (0)
-static inline void
-I915_DBG(unsigned flags, const char *fmt, ...)
-{
-}
-#endif
 
 void i915_debug_init(struct i915_screen *i915);