net: qcom/emac: extend DMA mask to 46bits

Bit TPD3[31] is used as a timestamp bit if PTP is enabled, but
it's used as an address bit if PTP is disabled.  Since PTP isn't
supported by the driver, we can extend the DMA address to 46 bits.

Signed-off-by: Wang Dongsheng <dongsheng.wang@hxt-semitech.com>
Acked-by: Timur Tabi <timur@codeaurora.org>
Signed-off-by: David S. Miller <davem@davemloft.net>