ARM: tegra: Initialize pll_p_out1

pll_a uses pll_p_out1 as its parent. Therefore this clock needs to be
initialized to make sure pll_a has a known input clock. Failure to do so
will cause the system to crash early in the bootup.

Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>