selftests/mqueue: fix 5 warnings about signed/unsigned mismatches

selftests/mqueue: fix 5 warnings about signed/unsigned mismatches

When building with clang, via:

    make LLVM=1 -C tools/testing/selftest

...clang warns about several cases of using a signed integer for the
priority argument to mq_receive(3), which expects an unsigned int.

Fix this by declaring the type as unsigned int in all cases.

Link: https://lkml.kernel.org/r/20240527200835.143682-1-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Valentin Obst <kernel@valentinobst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>