Tegra186: implement plat_get_syscnt_freq2()

Commit f3d3b316

 replaced
plat_get_syscnt_freq by plat_get_syscnt_freq2 on all the
upstream platforms. This patch modifies the Tegra186 code
which is not present usptream, yet.

Change-Id: Ieda6168050a7769680a3a94513637fed03463a2d
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>

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

@@ -114,7 +114,7 @@ const mmap_region_t *plat_get_mmio_map(void)
 /*******************************************************************************
  * Handler to get the System Counter Frequency
  ******************************************************************************/
-unsigned long long plat_get_syscnt_freq(void)
+unsigned int plat_get_syscnt_freq2(void)
 {
 	return 31250000;
 }