MAINTAINERS: wifi: brcm80211: remove non-existing SHA-cyfmac-dev-list@infineon.com

When sending an email to SHA-cyfmac-dev-list@infineon.com, the server
responds '550 #5.1.0 Address rejected.'

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20231218121105.23882-1-lukas.bulwahn@gmail.com