[][CRITICAL][kernel][common][eth][Fix SRAM allocation error for RX DMAD]

[Description]
Fix SRAM allocation error for RX DMAD.

Due to the incorrect method of allocation SRAM, it led the
use of SRAM size exceeding the expected range.

If without this patch, it may cause abnormalities in other
drivers using the same SRAM address.

[Release-log]
N/A


Change-Id: Idfe104f32be69e7684700fea507513f58c86365c
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8989469
1 file changed