Tegra: PMC: check if a CPU is already online

This patch checks if the target CPU is already online before
proceeding with it's power ON sequence.

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>

plat/nvidia/tegra/common/drivers/pmc/pmc.c

@@ -51,6 +51,13 @@ void tegra_pmc_cpu_on(int cpu)
 {
 	uint32_t val;
 
+	/*
+	 * Check if CPU is already power ungated
+	 */
+	val = tegra_pmc_read_32(PMC_PWRGATE_STATUS);
+	if (val & (1 << pmc_cpu_powergate_id[cpu]))
+		return;
+
 	/*
 	 * The PMC deasserts the START bit when it starts the power
 	 * ungate process. Loop till no power toggle is in progress.