Revert "niu: Add support for byte queue limits."

[ Upstream commit 6a2b28ef036ab5c66fdc606fe97d9e5cb34ea409 ]

This reverts commit efa230f2c68abab817f13473077f8d0cc74f43f3.

BQL doesn't work with how this driver currently only takes TX
interrupts every 1/4 of the TX ring.  That behavior needs to be fixed,
but that's a larger non-trivial task and for now we have to revert
BQL support as this makes the device currently completely unusable.

Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>