Staging: android: fix build error on 64bit boxes

ktime_t isn't ment to directly access on all arches, so use the proper
conversion functions instead to figure out what time is remaining.

Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Mike Lockwood <lockwood@android.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>