net: fs_enet: Remove has_phy field in fs_platform_info struct

Since commit 3dd82a1e ("[POWERPC] CPM: Always use new binding.")
has_phy field is never set.

Remove dead code and remove the field.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/bb5264e09e18f0ce8a0dbee399926a59f33cb248.1691155346.git.christophe.leroy@csgroup.eu


Signed-off-by: Jakub Kicinski <kuba@kernel.org>