wil6210: channel off by 1

WMI commands wants channel index, that is channel - 1

Signed-off-by: Vladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Git-commit: adc2d1225bed4bbf68473e6b5c4b91d2445609cb
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Liron Kuch <lkuch@codeaurora.org>