panfrost: don't expose 32K textures because st/mesa doesn't support them

st/mesa only supports 16k for renderbuffers and rectangle textures,
and increasing that to 32k breaks panfrost.

Reviewed-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/38587>

src/gallium/drivers/panfrost/pan_device.h

@@ -63,8 +63,11 @@ extern "C" {
 #define PAN_MAX_CONST_BUFFERS 16
 
 /* TODO: Mali hardware can texture up to 64k textures, but the
- * Gallium interface limits us to 32k at the moment */
-#define PAN_MAX_MIP_LEVELS 16
+ * Gallium interface limits us to 32k at the moment
+ * Also dEQP-GLES31.functional.fbo.no_attachments.maximums.all crashes with
+ * 32k textures.
+ */
+#define PAN_MAX_MIP_LEVELS 15
 
 /* How many power-of-two levels in the BO cache do we want? 2^12
  * minimum chosen as it is the page size that all allocations are