msm: ipa3: Fix to reduce user data size for WDI offloaded channels

For IPA offload WDI channel user_data not required. Reducing the
user_data size to minimum.

Change-Id: Id489171a9846e4f4f7eaac1847e8e4d3190efe54
Signed-off-by: Ashok Vuyyuru <avuyyuru@codeaurora.org>