wifi: b43: do not initialise static variable to 0

No need to initialise static variables to zero.

Signed-off-by: Xin Gao <gaoxin@cdjrlc.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
[kvalo@kernel.org: improve commit log]
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220720194245.8442-1-gaoxin@cdjrlc.com