mei: normalize timeouts definitions

1. The hardware book defines timeouts in seconds
 so we stick to this and define the wrapper function
 mei_secs_to_jiffies  around  msecs_to_jiffies
 to use be used instead multiplying by HZ

2. We add name space prefix MEI_ to all timer defines

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>