There are two utility functions to check if the association
is ESE or not. csr_neighbor_roam_is_ese_assoc() and
csr_roam_is_ese_assoc().
Both serves the same purpose, hence remove csr_neighbor_roam_is_ese_assoc()
and use csr_roam_is_ese_assoc().
Change-Id: I857f9c16eb73a4b0f72e0a622be47ab756fb70f4
CRs-Fixed: 950762