time: Move ktime_t overflow checking into timespec_valid_strict

time: Move ktime_t overflow checking into timespec_valid_strict

Andreas Bombe reported that the added ktime_t overflow checking added to
timespec_valid in commit 4e8b14526ca7 ("time: Improve sanity checking of
timekeeping inputs") was causing problems with X.org because it caused
timeouts larger then KTIME_T to be invalid.

Previously, these large timeouts would be clamped to KTIME_MAX and would
never expire, which is valid.

This patch splits the ktime_t overflow checking into a new
timespec_valid_strict function, and converts the timekeeping codes
internal checking to use this more strict function.

Reported-and-tested-by: Andreas Bombe <[email protected]>
Cc: Zhouping Liu <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Prarit Bhargava <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Signed-off-by: John Stultz <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>