optee: fix uninited async notif value

optee: fix uninited async notif value

Fixes an uninitialized variable in irq_handler() that could lead to
unpredictable behavior in case OP-TEE fails to handle SMC function ID
OPTEE_SMC_GET_ASYNC_NOTIF_VALUE. This change ensures that in that case
get_async_notif_value() properly reports there are no notification
event.

Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/202304200755.OoiuclDZ-lkp@intel.com/
Reported-by: Dan Carpenter <error27@gmail.com>
Link: https://lore.kernel.org/all/d9b7f69b-c737-4cb3-8e74-79fe00c934f9@kili.mountain/
Fixes: 6749e69c4dad ("optee: add asynchronous notifications")
Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>