drivers: rmnet: perf: lock around deag

Locking around deagg protects us against
hotplug events where a core goes down for
thermal reasons. Without this, we could get
race conditions which lead to double free
problems. This also covers case where paged
data is used over linear data.

Change-Id: I1c2ee97cfb37c44c7f6d64446af0736e1c431eff
Signed-off-by: Conner Huff <chuff@codeaurora.org>