ARM: tegra: fix pclk rate

Commit 40f9cf0 "ARM: tegra: reparent sclk to pll_c_out1" changed the
rate of hclk. Since pclk is derived from that, and only has integer
dividers, the pclk rate needs to change in the same fashion, from 54MHz
to 60MHz.

Signed-off-by: Stephen Warren <swarren@nvidia.com>