alsa-intf: fix pcm_open

The issue:
Qcom defined pcm_open as pcm_open(unsigned flags, char *device).
However, Qcom treated device as const char* in this case.

The solution:
Cast device as char*, removing const attribute

Qualcomm: If you implement a common definition, be sure to stick to it! Otherwise, you can inline ;)

Test Plan: verify (should be good)

Reviewers: jriordan001, randall.rushing, synergy

Reviewed By: synergy

Differential Revision: http://review.codefirex.com/D656