/bin/wifi: fix opt.band handling for Quantenna.

Commit e78c51a6b0f45b5ee1b1a6b73a56165c91f77f61 introduced a bug in
quantenna._stop where passing opt.band = '2.4 5' results in a false
error.

Change-Id: Ia412f5e4e07e50db6b65a3dfb0f50bd2dc16bbef
3 files changed