net: netcp: MAX_SKB_FRAGS is now 'int'

The type of MAX_SKB_FRAGS has changed recently, so the debug printk
needs to be updated:

drivers/net/ethernet/ti/netcp_core.c: In function 'netcp_create_interface':
drivers/net/ethernet/ti/netcp_core.c:2084:30: error: format '%ld' expects argument of type 'long int', but argument 3 has type 'int' [-Werror=format=]
 2084 |                 dev_err(dev, "tx-pool size too small, must be at least %ld\n",
      |                              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fixes: 3948b059 ("net: introduce a config option to tweak MAX_SKB_FRAGS")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>