msm: ipa : Fix KW array index issue on dbg_buff

KW raise the issue of "array 'dbg_buff' of size 4096
may use index value(s) 4096." The fix is to increase the
dbg_buff size to avoid it.

Change-Id: Ibb02e7fa73d9c0fb8924c90c66052255acc8275f
Signed-off-by: Bojun Pan <bojunp@codeaurora.org>