[BugFix][API-1476]update wifi FW 20 to 21

Affected branch:MR3.0-xx && GSW3.0

Affected module:wifi

Is it addected on both ZXIC and MTK: only MTK

Self-test: Yes

Doc Update: No

Change-Id: Ic5fdbf26d5ea40dc11c8ce414cdb24d82454a905
1 file changed