i40e: make const array patterns static, reduces object code size

Don't populate const array patterns on the stack, instead make it
static. Makes the object code smaller by over 60 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
   1953	    496	      0	   2449	    991	i40e_diag.o

After:
   text	   data	    bss	    dec	    hex	filename
   1798	    584	      0	   2382	    94e	i40e_diag.o

(gcc 6.3.0, x86-64)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>