igc: Remove convert_art_ns_to_tsc()

The core code now provides a mechanism to convert the ART base clock to the
corresponding TSC value without requiring an architecture specific
function.

Replace the direct conversion by filling in the required data.

No functional change intended.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240513103813.5666-5-lakshmi.sowjanya.d@intel.com