This is because drivers/net/fs_enet/fs_enet-main.c:fs_ioctl
disables the interrupts with spin_lock_irqsave after which it calls
phy_mii_ioctl. This leads to drivers/net/phy/phy.c:phy_read
being called which does spin_lock_bh/spin_unlock_bh.
Obviously the spin_unlock_bh enables softirqs and it is correctly
complaining irqs are disabled.
That's a programming error. The PHY Layer's functions must not be
called with interrupts disabled.
Andy