rtlwifi: fix uninitialized rtlhal->last_suspend_sec time

We set rtlhal->last_suspend_sec to an uninitialized stack variable,
but unfortunately gcc never warned about this, I only found it
while working on another patch. I opened a gcc bug for this.

Presumably the value of rtlhal->last_suspend_sec is not all that
important, but it does get used, so we probably want the
patch backported to stable kernels.

Cc: stable@vger.kernel.org
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82839


Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>