svga: SVGA_3D_CMD_BIND_GB_SHADER needs to reserve two relocations.

With this patch, the SVGA_3D_CMD_BIND_GB_SHADER functionality will reserve
two relocations, one for the shader ID and the second for the MOB ID.

Verified with the WDDM winsys path that the number of relocations and patch
locations required is two.

Fixes Bug 1277406

Reviewed-by: Charmaine Lee <charmainel@vmware.com>

src/gallium/drivers/svga/svga_cmd.c

@@ -1652,7 +1652,7 @@ SVGA3D_BindGBShader(struct svga_winsys_context *swc,
       SVGA3D_FIFOReserve(swc,
                          SVGA_3D_CMD_BIND_GB_SHADER,
                          sizeof *cmd,
-                         1);  /* one relocation */
+                         2);  /* two relocations */
 
    if (!cmd)
       return PIPE_ERROR_OUT_OF_MEMORY;