mempool: adjust name size in related data types

mempool: adjust name size in related data types

A recent patch brought up an issue about the size of the 'name' fields:

85cf0079 mem: avoid memzone/mempool/ring name truncation

These relations should be observed:

1. Each ring creates a memzone with a prefixed name:
RTE_RING_NAMESIZE <= RTE_MEMZONE_NAMESIZE - strlen(RTE_RING_MZ_PREFIX)

2. There are some mempool handlers which create a ring with a prefixed
name:
RTE_MEMPOOL_NAMESIZE <= RTE_RING_NAMESIZE - strlen(RTE_MEMPOOL_MZ_PREFIX)

3. A mempool can create up to RTE_MAX_MEMZONE pre and postfixed memzones:
sprintf(postfix, "_%d", RTE_MAX_MEMZONE)
RTE_MEMPOOL_NAMESIZE <= RTE_MEMZONE_NAMESIZE -
	strlen(RTE_MEMPOOL_MZ_PREFIX) - strlen(postfix)

Setting all of them to 32 hides this restriction from the application.
This patch decreases the mempool and ring string size to accommodate for
these prefixes, but it doesn't apply the 3rd constraint. Applications
relying on these constants need to be recompiled, otherwise they'll run
into ENAMETOOLONG issues.
The size of the arrays are kept 32 for ABI compatibility, it can be
decreased next time the ABI changes.

Signed-off-by: Zoltan Kiss <zoltan.kiss@schaman.hu>
Acked-by: Olivier Matz <olivier.matz@6wind.com>