qtnfmac: Remove unused macro QTNF_DMP_MAX_LEN

There is no caller in tree, so remove it.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200909135951.4028-1-yuehaibing@huawei.com