Use previously refactored code and create a function
that allows XDP code to read HW timestamp.

Also, introduce packet context, where hints-related data will be stored.
ice_xdp_buff contains only a pointer to this structure, to avoid copying it
in ZC mode later in the series.

HW timestamp is the first supported hint in the driver,
so also add xdp_metadata_ops.
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
Link: https://lore.kernel.org/r/20231205210847.28460-6-larysa.zaremba@intel.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>