The return values are not used by callers of these functions
so change the functions to return void.

Other miscellanea:

o add __printf verification to wil6210 logging functions
  No format/argument mismatches found
Acked-by: NVladimir Kondratiev <qca_vkondrat@qca.qualcomm.com>
Signed-off-by: NJoe Perches <joe@perches.com>
Signed-off-by: NKalle Valo <kvalo@qca.qualcomm.com>