cnss_utils: Increase unsafe channel max num for 6G

2G+5G+6G, total channel num is 157 until now, increase unsafe channel max
num to avoid out of buffer.

Change-Id: I1e433c0bd88290bb5493b2c4b0bda86e17b04a01
CRs-Fixed: 2752689
Signed-off-by: Jianmin Zhu <jianminz@codeaurora.org>
Signed-off-by: Manikandan Mohan <manikand@codeaurora.org>