radv: Add radv_enable_float16_gfx8 drirc and enable for Indiana Jones TGC

This is a hard requirement from the game preventing it to start on GFX8.
Adding this allows playing it on GFX8.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34114>

src/util/00-radv-defaults.conf

@@ -115,6 +115,7 @@ Application bugs worked around in this file:
             <option name="radv_invariant_geom" value="true" />
             <option name="radv_lower_terminate_to_discard" value="true" />
             <option name="radv_emulate_rt" value="true" />
+            <option name="radv_enable_float16_gfx8" value="true" />
         </application>
 
         <application name="DOOM (2016)" application_name_match="DOOM$">

src/util/driconf.h

@@ -802,6 +802,10 @@
    DRI_CONF_OPT_B(radv_emulate_rt, def, \
                   "Expose RT extensions on GFX10 and below through software emulation.")
 
+#define DRI_CONF_RADV_ENABLE_FLOAT16_GFX8(def) \
+   DRI_CONF_OPT_B(radv_enable_float16_gfx8, def, \
+                  "Expose float16 on GFX8, where it's supported but usually not beneficial.")
+
 /**
  * \brief ANV specific configuration options
  */