net: socket: Add support for SO_TIMESTAMPING socket level option

This is the last commit of the set of patches that introduces
`SO_TIMESTAMPING` socket level optino in Zephyr. The patch
adds `SOF_TIMESTAMPING_RX_HARDWARE` and `SOF_TIMESTAMPING_TX_HARDWARE`
bitmasks. It can be extedned in the future to cover more timestamping
features. Currently the feature can be used with ptp_clock driver.

Signed-off-by: Adam Wojasinski <awojasinski@baylibre.com>