esoc: Fix a uninitalized variable warning

Fix an uninitalized variable compiler warning from last_esoc_req_show().

Fixes: f2e94fd8 ("esoc: Add snapshot of esoc driver")
Change-Id: Ic0dedbad09da5c9d1ab5d2897ec16b27966f0ebb
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>