CVE request: kernel: timekeeping: Prevent oops when GENERIC_TIME=n

[Eugene Teo <eugeneteo () kernel sg>]

"Aaro Koskinen reported an issue in kernel.org bugzilla #15366, where on 
non-GENERIC_TIME systems, accessing 
/sys/devices/system/clocksource/clocksource0/current_clocksource results 
in an oops.

It seems the timekeeper/clocksource rework missed initializing the 
curr_clocksource value in the !GENERIC_TIME case."

Upstream commit:
http://git.kernel.org/linus/ad6759fbf35d104dbf573cd6f4c6784ad6823f7e

I believe distros are using GENERIC_TIME=y, at least this is the case in 
our supported kernels.

Thanks, Eugene
--
main(i) { putchar(182623909 >> (i-1) * 5&31|!!(i<7)<<6) && main(++i); }