bootperf: fix running with non-default output directory

This fixes a bug in the bootperf script that uses $PWD as the output
directory even if the user specifies the output directory with the -o
option.

BUG=b:186298152
TEST=bootperf -o ~/bootperf-out $IP_ADDR && bootperf -o ~/bootperf-out
$IP_ADDR && showbootdata ~/bootperf-out

Change-Id: I4ba64d7c1ea2f71611c270286fa45b4366fb47b6
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crostestutils/+/2852639
Reviewed-by: Grant Grundler <grundler@chromium.org>
Tested-by: Chinglin Yu <chinglinyu@chromium.org>
Tested-by: Grant Grundler <grundler@chromium.org>
Commit-Queue: Grant Grundler <grundler@chromium.org>
1 file changed