msm: ais: 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).

Change-Id: Iccf02b68314e770ad9fae41973cad6ff7700b822
Signed-off-by: E V Ravi <evenka@codeaurora.org>