configs: remove CONFIG_ASIX_PHY
The Kconfig symbol ASIX_PHY was renamed to AX88796B_PHY in v5.2-rc6, see
upstream commit a9520543b123 ("net: phy: rename Asix Electronics PHY
driver"). CONFIG_AX88796B_PHY is already used in the configuration generation
system, so we can safely remove CONFIG_ASIX_PHY from that system.
Signed-off-by: Paul Bolle <pebolle@tiscali.nl>