tegra: Init clocks even when SPL did not run

At present early clock init happens in SPL. If SPL did not run (because
for example U-Boot is chain-loaded from another boot loader) then the
clocks are not set as U-Boot expects.

Add a function to detect this and call the early clock init in U-Boot
proper.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/mach-tegra/board2.c b/arch/arm/mach-tegra/board2.c
index 84f1ee5..1e627ba 100644
--- a/arch/arm/mach-tegra/board2.c
+++ b/arch/arm/mach-tegra/board2.c
@@ -191,6 +191,9 @@
 
 int board_early_init_f(void)
 {
+	if (!clock_early_init_done())
+		clock_early_init();
+
 #if defined(CONFIG_TEGRA_DISCONNECT_UDC_ON_BOOT)
 #define USBCMD_FS2 (1 << 15)
 	{