posix-cpu-timers: fix clock_gettime with CLOCK_PROCESS_CPUTIME_ID

Since CLOCK_PROCESS_CPUTIME_ID is in fact translated to -6, the switch
statement in cpu_clock_sample_group() must first mask off the irrelevant
bits, similar to cpu_clock_sample().

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
--
 posix-cpu-timers.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)