clk: qoriq: add LS1021A core pll mux options

This allows to clock the cores with 1 GHz, 500 MHz and 250 MHz.

Signed-off-by: Michael Krummsdorf <michael.krummsdorf@tq-group.com>
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Link: https://lore.kernel.org/r/20200610113837.27117-1-matthias.schiffer@ew.tq-group.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>