shared/ethtool-util: autogenerate table of link mode names

shared/ethtool-util: autogenerate table of link mode names

We updated this table manually, but the kernel adds new modes periodically
and we forget to do that. So let that happen automatically whenever we import
new kernel headers.

C.f. 72dda93acba95a330daae45bd85be8abc788df1c.

Effectively, this adds:
        [ETHTOOL_LINK_MODE_10baseT1L_Full_BIT]             = "10baset1l-full",
        [ETHTOOL_LINK_MODE_800000baseCR8_Full_BIT]         = "800000basecr8-full",
        [ETHTOOL_LINK_MODE_800000baseKR8_Full_BIT]         = "800000basekr8-full",
        [ETHTOOL_LINK_MODE_800000baseDR8_Full_BIT]         = "800000basedr8-full",
        [ETHTOOL_LINK_MODE_800000baseDR8_2_Full_BIT]       = "800000basedr8-2-full",
        [ETHTOOL_LINK_MODE_800000baseSR8_Full_BIT]         = "800000basesr8-full",
        [ETHTOOL_LINK_MODE_800000baseVR8_Full_BIT]         = "800000basevr8-full",

N_ADVERTISE needed to be increased because we need more bits.