net: bgmac: Fix endian access in bgmac_dma_tx_ring_free()

net: bgmac: Fix endian access in bgmac_dma_tx_ring_free()

[ Upstream commit 60d6e6f0b9e422dd01aeda39257ee0428e5e2a3f ]

bgmac_dma_tx_ring_free() assigns the ctl1 word which is a litle endian
32-bit word without using proper accessors, fix this, and because a
length cannot be negative, use unsigned int while at it.

Fixes: 9cde94506eac ("bgmac: implement scatter/gather support")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>