cml1.bbclass: Only delay exit if the command fails

cml1.bbclass: Only delay exit if the command fails

Rather than pause for 5 seconds, test the return code of the command and
require user input before exiting on failure. This avoids pausing after
successful command execution as well as possibly not waiting long enough
if the user happens to be doing something else for 5 seconds.

(From OE-Core rev: d99cc2b70bbda9a0cbc09a4430b871c287113041)

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>