pcm_hw: Fix buffer overflow in chmap

We can't calculate memory storage in bytes, when we're supposed
to store ints in it!

Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
pcm_direct: fix SEGFAULT when getgrnam_r() returns 0 and pgrp is NULL

Signed-off-by: Krzysztof Halasa <khalasa@piap.pl>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>