Documentation/ABI: Add new attributes for mlxreg-io sysfs interfaces

Add documentation for the new attributes:
- "phy_reset" - Reset PHY.
- "mac_reset" - Reset MAC.
- "qsfp_pwr_good" - The power status of QSFP ports.

Signed-off-by: Michael Shych <michaelsh@nvidia.com>
Reviewed-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20220430115809.54565-4-michaelsh@nvidia.com


Signed-off-by: Hans de Goede <hdegoede@redhat.com>