[][MAC80211][app][Update smp-mp76.sh 4-RSS scenario for the mt7986]

[Description]
Refactor smp-mp76.sh 4-RSS scenario for the mt7986.

Without this patch, all the RSS interrupts (4 Rx rings) would be
assigned to the same CPU.

[Release-log]
N/A


Change-Id: I415db025af12e160f8f0506271142f1cf7512bd9
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8029454
1 file changed