ALSA: pcm: check for integer overflow during multiplication

Channel info data structure is parsed from userspace and if
user does not set the no. of channels correctly, it could lead
to security vulnerability if we don't check for overflow when the
no. of channels is multiplied with pcm bit width. Add a condition
to check for overflow during multiplication.

CRs-fixed: 537818
Change-Id: Ia3c31406dd8b7627ea704c076643c0348582da28
Signed-off-by: Phani Kumar Uppalapati <phaniu@codeaurora.org>