v3d: implement geometry shader instancing

v2:
 - Remove unused field uses_iid from v3d_gs_prog_data (Alejandro)

Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>

src/broadcom/compiler/v3d_compiler.h

@@ -718,6 +718,9 @@ struct v3d_gs_prog_data {
 
         /* Output primitive type */
         uint8_t out_prim_type;
+
+        /* Number of GS invocations */
+        uint8_t num_invocations;
 };
 
 struct v3d_fs_prog_data {
@@ -1037,6 +1040,7 @@ VIR_A_ALU2(LDVPMG_IN)
 VIR_A_ALU2(LDVPMG_OUT)
 VIR_A_ALU0(TMUWT)
 
+VIR_A_ALU0(IID)
 VIR_A_ALU0(FXCD)
 VIR_A_ALU0(XCD)
 VIR_A_ALU0(FYCD)