ath10k: Fix dst CE ring configuration for CE5

CE5 ring is not used in current configuration for
WCN3990 chipset. Set the entries to zero to avoid
unnecessary allocation during driver load.

CRs-Fixed: 2082022
Change-Id: I992f0fb3b5c2bc6d6fd067bb23e67b23a12ffdb7
Signed-off-by: Govind Singh <govinds@codeaurora.org>