selftests/arm64: Remove casts to/from void in check_tags_inclusion

Void pointers may be freely used with other pointer types in C, any casts
between void * and other pointer types serve no purpose other than to
mask potential warnings. Drop such casts from check_tags_inclusion to
help with future review of the code.

Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20220510164520.768783-5-broonie@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>