kunit/overflow: Fix UB in overflow_allocation_test

kunit/overflow: Fix UB in overflow_allocation_test

The 'device_name' array doesn't exist out of the
'overflow_allocation_test' function scope. However, it is being used as
a driver name when calling 'kunit_driver_create' from
'kunit_device_register'. It produces the kernel panic with KASAN
enabled.

Since this variable is used in one place only, remove it and pass the
device name into kunit_device_register directly as an ascii string.

Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Reviewed-by: David Gow <davidgow@google.com>
Link: https://lore.kernel.org/r/20240815000431.401869-1-ivan.orlov0322@gmail.com
Signed-off-by: Kees Cook <kees@kernel.org>