test/README.md: Update access permissions

The default access permission for the README.md file should be 664.

Signed-off-by: George Liu <liuxiwei@ieisystem.com>
Change-Id: Ia2c14646fd99eab3a580b1c276a46ff2f604b1ae
diff --git a/test/README.md b/test/README.md
old mode 100755
new mode 100644