profiler: Fix Possible memory leak

Avoid possible memory leak by the dynamic memory stored in 'bwbuf'
allocated through function 'kzalloc' when met with error condition
and function return.

Change-Id: I87607bf64e75ada7a8062bb28585eda26cdfbfbd
Signed-off-by: Jaiju Yesudasan <cjaijuy@codeaurora.org>