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: NColin Ian King <colin.king@canonical.com>
Acked-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_diag.c

@@ -36,7 +36,9 @@
 static i40e_status i40e_diag_reg_pattern_test(struct i40e_hw *hw,
 							u32 reg, u32 mask)
 {
-	const u32 patterns[] = {0x5A5A5A5A, 0xA5A5A5A5, 0x00000000, 0xFFFFFFFF};
+	static const u32 patterns[] = {
+		0x5A5A5A5A, 0xA5A5A5A5, 0x00000000, 0xFFFFFFFF
+	};
 	u32 pat, val, orig_val;
 	int i;