Don't populate the array template  on the stack but instead make it
static. Makes the object code smaller by 10 bytes. Also reformat
the declaration.

Before:
   text	   data	    bss	    dec	    hex	filename
  29376	   9360	    128	  38864	   97d0	drivers/hid/hid-logitech-dj.o

After:
   text	   data	    bss	    dec	    hex	filename
  29270	   9456	    128	  38854	   97c6	drivers/hid/hid-logitech-dj.o

(gcc version 8.3.0, amd64)
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>