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: Ib9631b6e45d77b39be2c27343d4aee3e9244d8cc
Signed-off-by: Phani Kumar Uppalapati <phaniu@codeaurora.org>