perf script: Fix --max-blocks man page description

The --max-blocks description was using the old name brstackasm.  Use
brstackinsn instead.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20190711181922.18765-1-andi@firstfloor.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-script.txt

@@ -384,7 +384,7 @@ include::itrace.txt[]
 	perf script --time 0%-10%,30%-40%
 
 --max-blocks::
-	Set the maximum number of program blocks to print with brstackasm for
+	Set the maximum number of program blocks to print with brstackinsn for
 	each sample.
 
 --reltime::