netdevsim: make array res_ids static const, makes object smaller

Don't populate the array res_ids on the stack but instead it
static const. Makes the object code smaller by 14 bytes.

Before:
   text    data     bss     dec     hex filename
  50833    8314     256   59403    e80b ./drivers/net/netdevsim/fib.o

After:
   text    data     bss     dec     hex filename
  50755    8378     256   59389    e7fd ./drivers/net/netdevsim/fib.o

(gcc version 10.2.0)

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lore.kernel.org/r/20210801065328.138906-1-colin.king@canonical.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>