time: Prevent 32 bit overflow with set_normalized_timespec()

set_normalized_timespec() nsec argument is of type long. The recent
timekeeping changes of ktime_get_ts() feed 

	ts->tv_nsec + tomono.tv_nsec + nsecs

to set_normalized_timespec(). On 32 bit machines that sum can be
larger than (1 << 31) and therefor result in a negative value which
screws up the result completely.

Make the nsec argument of set_normalized_timespec() s64 to fix the
problem at hand. This also prevents similar problems for future users
of set_normalized_timespec().

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Carsten Emde <carsten.emde@osadl.org>
LKML-Reference: <new-submission>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: John Stultz <johnstul@us.ibm.com>