ARM: k2e/l: Apply WA for selecting PA clock source

ARM: k2e/l: Apply WA for selecting PA clock source

On keystone2 Lamarr and Edison platforms, the PA clocksource
mux in PLL REG1, can be changed only after enabling its clock
domain.
So selecting the output of PASS PLL as input to PA only after
enabling the clockdomain.
This is as per the debug done by "Vitaly Andrianov <vitalya@ti.com>"
and based on the previous work done by "Hao Zhang <hzhang@ti.com>"

Fixes: d634a0775bcf ("ARM: keystone2: Cleanup PLL init code")
Reported-by: Vitaly Andrianov <vitalya@ti.com>
Tested-by: Vitaly Andrianov <vitalya@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>