Fix a small compiler warning.

nr_process must be a signed long: it is assigned a signed long by
strtol() and is compared against LONG_MIN and LONG_MAX.

ipsec.c:2280:65:
    error: result of comparison of constant -9223372036854775808
    with expression of type 'unsigned int' is always false
    [-Werror,-Wtautological-constant-out-of-range-compare]

  if ((errno == ERANGE && (nr_process == LONG_MAX || nr_process == LONG_MIN))

Fixes: bc2652b7 ("selftest/net/xfrm: Add test for ipsec tunnel")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Dmitry Safonov <0x7f454c46@gmail.com>
Link: https://lore.kernel.org/r/20231124171645.1011043-2-willemdebruijn.kernel@gmail.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>