dirconf: add a common vk_zero_vram

This adds a vk_zero_vram dri conf.
Vulkan drivers needs this to run several games.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29892>

src/util/driconf.h

@@ -496,6 +496,10 @@
    DRI_CONF_OPT_B(no_fp16, def, \
                   "Disable 16-bit float support")
 
+#define DRI_CONF_VK_ZERO_VRAM(def) \
+   DRI_CONF_OPT_B(vk_zero_vram, def, \
+                  "Initialize to zero all VRAM allocations")
+
 /**
  * \brief Initialization configuration options
  */