net: ti: icss-iep: Add phase offset configuration for perout signal

icss_iep_perout_enable_hw() is a common function for generating
both pps and perout signals. When enabling pps, the application needs
to only pass enable/disable argument, whereas for perout it supports
different flags to configure the signal.

In case the app passes a valid phase offset value, the signal should
start toggling after that phase offset, else start immediately or
as soon as possible. ICSS_IEP_SYNC_START_REG register take number of
clock cycles to wait before starting the signal after activation time.
Set appropriate value to this register to support phase offset.

Signed-off-by: Meghana Malladi <m-malladi@ti.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20250304105753.1552159-3-m-malladi@ti.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>