[][kernel][mt7988][eth][Enhance the TX performance of the QDMA]

[Description]
Change QDMA_BT_SIZE to 16DWORDS to enhance the TX performance of the
QDMA.

Without this patch, the test for the 512B packets no drop may have
failed.

[Release-log]
N/A


Change-Id: I68f063d1c18b3be5792f746d3ad152dff09b74ce
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8832404
2 files changed