clk: tegra: Allow PLLE training to succeed

Under some circumstances the PLLE needs to be retrained, in which case
access to the PMC registers is required. Fix this by passing a pointer
to the PMC registers instead of NULL when registering the PLLE clock.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Acked-By: Peter De Schrijver <pdeschrijver@nvidia.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>