dpdk: Use default drivers_install_subdir value

[remidebord-airbus]

When dynamic linking is used, eal_plugins_init is called and leads to the dlopen of all the libraries included in /usr/lib/.
By consequence you could have such errors:

root@lx2160ardb-rev2:~# ./helloworld
EAL: Detected CPU lcores: 16
EAL: Detected NUMA nodes: 1
EAL: Detected shared linkage of DPDK
EAL: /usr/lib/libthread_db.so.1: undefined symbol: ps_pdwrite
EAL: FATAL: Cannot init plugins
EAL: Cannot init plugins
PANIC in main():
Cannot init EAL
0: /usr/lib/librte_eal.so.23 (rte_dump_stack+0x3c) [ffff82c1e0bc]
1: /usr/lib/librte_eal.so.23 (__rte_panic+0xb8) [ffff82bfded8]
2: ./helloworld (aaaab3dc0000+0xa44) [aaaab3dc0a44]
3: /usr/lib/libc.so.6 (ffff82a40000+0x284f4) [ffff82a684f4]
4: /usr/lib/libc.so.6 (__libc_start_main+0x9c) [ffff82a685cc]
5: ./helloworld (aaaab3dc0000+0xab0) [aaaab3dc0ab0]

In order to avoid that, put those drivers into a dedicated directory, like the one defined by default (dpdk/pmds-<VERSION>) in the DPDK meson options file.

[thochstein]

Thanks, looks good to me :-)