modpost: file2alias: check prototype of handler

[ Upstream commit f880eea68fe593342fa6e09be9bb661f3c297aec ]

Use specific prototype instead of an opaque pointer so that the
compiler can catch function prototype mismatch.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>