tegra2: Add more clock functions

This adds most of the clock functions required by board and driver code:

-query and adjust peripheral clocks
-query and adjust PLLs
-reset and enable control

These functions are plumbed in as required.

Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Tom Warren <twarren@nvidia.com>
diff --git a/drivers/mmc/tegra2_mmc.h b/drivers/mmc/tegra2_mmc.h
index 4b80f9f..28698e0 100644
--- a/drivers/mmc/tegra2_mmc.h
+++ b/drivers/mmc/tegra2_mmc.h
@@ -73,6 +73,7 @@
 	unsigned int version;	/* SDHCI spec. version */
 	unsigned int clock;	/* Current clock (MHz) */
 	unsigned int base;	/* Base address, SDMMC1/2/3/4 */
+	enum periph_id mmc_id;	/* Peripheral ID: PERIPH_ID_... */
 };
 
 int tegra2_mmc_init(int dev_index, int bus_width);