[LTP] [PATCH][utimensat.sh] cd to tmp directory before copying to prevent deleting original utimensat binary

[Henry Y. <hy...@mv...>]

This patch makes the test script cd into the tmp directory before running
the tests. This makes sure the script does not delete the original utimensat
binary, causing the test to fail on a second run.

Signed-off-by: Henry Yei<hy...@mv...>