ath11k: Fix 'unused-but-set-parameter' error

Below compilation error is reported when built with W=1,

drivers/net/wireless/ath/ath11k/mac.c:5408:22: error: parameter 'changed_flags' set but not used [-Werror,-Wunused-but-set-parameter]

changed_flags is set, but left unused. So, remove unnecessary set.
Compile tested only.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Seevalamuthu Mariappan <quic_seevalam@quicinc.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1636609967-5114-1-git-send-email-quic_seevalam@quicinc.com