panfrost: add PAN_MAX_TEXEL_BUFFER_ELEMENTS define

We're going to be repeating this value a few places, so let's use a
single define to keep thing simple.

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28908>

src/gallium/drivers/panfrost/pan_device.h

@@ -62,6 +62,8 @@ extern "C" {
  */
 #define PAN_MAX_MIP_LEVELS 14
 
+#define PAN_MAX_TEXEL_BUFFER_ELEMENTS 65536
+
 /* 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
  * rounded to */

src/gallium/drivers/panfrost/pan_screen.c

@@ -214,7 +214,7 @@ panfrost_get_param(struct pipe_screen *screen, enum pipe_cap param)
          return 0;
 
    case PIPE_CAP_MAX_TEXEL_BUFFER_ELEMENTS_UINT:
-      return 65536;
+      return PAN_MAX_TEXEL_BUFFER_ELEMENTS;
 
    /* Must be at least 64 for correct behaviour */
    case PIPE_CAP_TEXTURE_BUFFER_OFFSET_ALIGNMENT: