eal: -n or -r options are ignored when --in-memory is used

[Igor Gutorov <igootorov@gmail.com>]

Hi,

I've noticed an issue of `rte_memory_get_nchannel()` or
`rte_memory_get_nrank()` always returning zero regardless of the -n or
-r options set.

I think this is due to `--in-memory` forcing `conf->no_shconf = 1`
[1], which leads to `rte_eal_memdevice_init()` never being executed
[2].

I do not fully understand the context of the code, but I can submit a
patch that simply removes the `internal_conf->no_shconf == 0` check in
`rte_eal_memory_init()` and so always calls
`rte_eal_memdevice_init()`. Would that be ok or is there a better way?
Alternatively, does `(internal_conf->no_shconf == 0 ||
internal_conf->in_memory == 1) && ...` make sense here?


And one more thing, the 9.1.4 section of the getting started guide
states that the number of memory ranks is auto-detected by default,
but I can't find any code that performs the auto-detection - am I
missing something, or is the documentation wrong here?

[1]: https://github.com/DPDK/dpdk/blob/3ee7a3e0e0e0f5a81a4b102a834697bc488fb32f/lib/eal/common/eal_common_options.c#L1815
[2]: https://github.com/DPDK/dpdk/blob/3ee7a3e0e0e0f5a81a4b102a834697bc488fb32f/lib/eal/common/eal_common_memory.c#L1103