GRTIMER: added to GPTIMER driver

GRTIMER is compatible with GPTIMER, however the GPTIMER driver
does not support the extended features of GRTIMER.

c/src/lib/libbsp/sparc/shared/timer/gptimer.c

@@ -141,6 +141,7 @@ struct drvmgr_drv_ops gptimer_ops =
 struct amba_dev_id gptimer_ids[] =
 {
 	{VENDOR_GAISLER, GAISLER_GPTIMER},
+	{VENDOR_GAISLER, GAISLER_GRTIMER},
 	{0, 0}		/* Mark end of table */
 };