riscv: timer: Add support for an early timer

Added support for timer_early_get_count() and timer_early_get_rate()
This is mostly useful in tracing.

Signed-off-by: Pragnesh Patel <pragnesh.patel@sifive.com>
Reviewed-by: Rick Chen <rick@andestech.com>
diff --git a/include/configs/sifive-fu540.h b/include/configs/sifive-fu540.h
index c1c79db..0d69d1c 100644
--- a/include/configs/sifive-fu540.h
+++ b/include/configs/sifive-fu540.h
@@ -36,6 +36,11 @@
 
 #define CONFIG_STANDALONE_LOAD_ADDR	0x80200000
 
+#define RISCV_MMODE_TIMERBASE		0x2000000
+#define RISCV_MMODE_TIMER_FREQ		1000000
+
+#define RISCV_SMODE_TIMER_FREQ		1000000
+
 /* Environment options */
 
 #ifndef CONFIG_SPL_BUILD