file-posix: remove incorrect coroutine_fn calls

file-posix: remove incorrect coroutine_fn calls

raw_co_getlength is called by handle_aiocb_write_zeroes, which is not a coroutine
function.  This is harmless because raw_co_getlength does not actually suspend,
but in the interest of clarity make it a non-coroutine_fn that is just wrapped
by the coroutine_fn raw_co_getlength.  Likewise, check_cache_dropped was only
a coroutine_fn because it called raw_co_getlength, so it can be made non-coroutine
as well.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20230601115145.196465-2-pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>