net: wireless: make a const array static, makes object smaller

Don't populate the const array bws on the stack but instead it
static. Makes the object code smaller by 80 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
  85694	  16865	   1216	 103775	  1955f	./net/wireless/reg.o

After:
   text	   data	    bss	    dec	    hex	filename
  85518	  16961	   1216	 103695	  1950f	./net/wireless/reg.o

(gcc version 10.2.0)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20201116181636.362729-1-colin.king@canonical.com


Signed-off-by: Johannes Berg <johannes.berg@intel.com>