Tegra: flowctrl: rename tegra_fc_cpu_idle() to tegra_fc_cpu_powerdn()

This patch renames the tegra_fc_cpu_idle() function to a more appropriate
tegra_fc_cpu_powerdn() to better reflect its usage.

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
diff --git a/plat/nvidia/tegra/common/drivers/flowctrl/flowctrl.c b/plat/nvidia/tegra/common/drivers/flowctrl/flowctrl.c
index b473dd6..3571758 100644
--- a/plat/nvidia/tegra/common/drivers/flowctrl/flowctrl.c
+++ b/plat/nvidia/tegra/common/drivers/flowctrl/flowctrl.c
@@ -98,9 +98,9 @@
 }
 
 /*******************************************************************************
- * Suspend the current CPU
+ * Powerdn the current CPU
  ******************************************************************************/
-void tegra_fc_cpu_idle(uint32_t mpidr)
+void tegra_fc_cpu_powerdn(uint32_t mpidr)
 {
 	int cpu = mpidr & MPIDR_CPU_MASK;