lib/crypto: tests: Annotate worker to be on stack

lib/crypto: tests: Annotate worker to be on stack

The following warning traceback is seen if object debugging is enabled
with the new crypto test code.

ODEBUG: object 9000000106237c50 is on stack 9000000106234000, but NOT annotated.
------------[ cut here ]------------
WARNING: lib/debugobjects.c:655 at lookup_object_or_alloc.part.0+0x19c/0x1f4, CPU#0: kunit_try_catch/468
...

This also results in a boot stall when running the code in qemu:loongarch.

Initializing the worker with INIT_WORK_ONSTACK() fixes the problem.

Fixes: 950a81224e8b ("lib/crypto: tests: Add hash-test-template.h and gen-hash-testvecs.py")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250721231917.3182029-1-linux@roeck-us.net
Signed-off-by: Eric Biggers <ebiggers@kernel.org>