ti: icssg: convert to ndo_hwtstamp API

ti: icssg: convert to ndo_hwtstamp API

Convert driver to use .ndo_hwtstamp_get()/.ndo_hwtstamp_set() API.
.ndo_eth_ioctl() implementation becomes pure phy_do_ioctl(), remove
it from common module, remove exported symbol and replace ndo callback.

Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://patch.msgid.link/20251016152515.3510991-3-vadim.fedorenko@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>