Tegra186: update SYSCNT_FREQ to 31.25MHz

The System Counter Frequency has been updated to 31.25MHz after
some experiments as the previous value was too high.

Change-Id: I79986ee1c0c88700a3a2b1dbff2d3f00c0c412b9
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>

plat/nvidia/tegra/soc/t186/plat_setup.c

@@ -69,7 +69,7 @@ const mmap_region_t *plat_get_mmio_map(void)
  ******************************************************************************/
 unsigned int plat_get_syscnt_freq2(void)
 {
-	return 38400000;
+	return 31250000;
 }
 
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