Correct address_space when casting ref of local variable to multi_ptr

[oleksandr-pavlyk]

Used address_space_cast<address_space::private_space,...> on a local variable.

To create the sycl::multi_ptr from a local variable (in private memory) we should be using address_space::private_space.

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Array API standard conformance tests for dpctl=0.14.6dev4=py310ha25a700_48 ran successfully.
Passed: 916
Failed: 84
Skipped: 119

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