The default values set by xran for DPDK socket memory/limit is 8192. It
is changed when the variable for the memory size, given down to xran, is
non-zero (cf also previous patch). Since the last patch, if nothing is
given in OAI configuration, OAI will pass down a size of 8192. However,
a configuration value of 0 is a valid choice (it is a pre-allocation,
DPDK will allocate dynamically), so modify the default in xran to be 0
so that all sizes, including 0, can be given to DPDK.

Note that the currently used implementation of xran will always try to
allocate this memory on NUMA node 0. If you want to use another one,
this field has to be set to 0 (no pre-allocation), and DPDK will
allocate it dynamically.
Co-authored-by: Sagar Arora <sagar.arora@openairinterface.org>