Staging: heci: fix typos and add wait after disconnect

- Fix typo for enum HECI_WRITE.
 - Fix timeout issue. If the time period is greater or equal 15s, it's timeout.
 - Add 10ms wait time after disconnect, to ensure that hardware is ready.
   Otherwise in the next time connection, hardware resource may be busy.

Signed-off-by: Dongxiao Xu <dongxiao.xu@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>