usb: gadget: udc: renesas_usb3: make const array max_packet_array static

Don't populate the const array max_packet_array on the stack, instead make
it static. Makes the object code smaller by over 90 bytes:

Before:
   text	   data	    bss	    dec	    hex	filename
  34337	   5612	    128	  40077	   9c8d	renesas_usb3.o

After:
   text	   data	    bss	    dec	    hex	filename
  34149	   5708	    128	  39985	   9c31	renesas_usb3.o

(gcc version 7.2.0 x86_64)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>