Use pll_ref instead of pll_re_vco as the pll_e parent on Tegra114. Also
add a 12Mhz pll_ref table entry for pll_e for Tegra114. This prevents
the system from crashing at bootup because of an unsupported pll_re_vco
rate.
Signed-off-by: NPeter De Schrijver <pdeschrijver@nvidia.com>