msm: camera: fix off-by-one overflow in msm_isp_get_bufq

In msm_isp_get_bufq, if bufq_index == buf_mgr->num_buf_q,
it will pass the check, leading to off-by-one overflow
(exceed the length of array by one element).

CRs-Fixed: 2031677
Change-Id: I7ea465897e2c37de6ca0155c3e225f1444b3cf13
Signed-off-by: Gaoxiang Chen <gaochen@codeaurora.org>