cputime: Constify timeval_to_cputime(timeval) argument

Saw the following compiler warning on the linux-next tree:

  kernel/itimer.c: In function 'set_cpu_itimer':
  kernel/itimer.c:152:2: warning: passing argument 1 of 'timeval_to_cputime' discards 'const' qualifier from pointer target type [enabled by default]
  ...

timeval_to_cputime() is always passed a constant timeval in
argument, we need to teach the nsecs based cputime
implementation about that.

Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Kevin Hilman <khilman@linaro.org>
Link: http://lkml.kernel.org/r/1361636925-22288-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Kevin Hilman <khilman@linaro.org>

include/asm-generic/cputime_nsecs.h

@@ -76,7 +76,7 @@ static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)
 /*
  * Convert cputime <-> timeval (msec)
  */
-static inline cputime_t timeval_to_cputime(struct timeval *val)
+static inline cputime_t timeval_to_cputime(const struct timeval *val)
 {
 	u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_usec * NSEC_PER_USEC;
 	return (__force cputime_t) ret;