softlockup: stop softlockup messages due to touch_ts math overflow
This patch will fix a math overflow error that causes spurious soft
lockup error messages. It catches a corner case, for example, just when
the TSC heads towards a 64 bit wrap-around when the upper 32 bits are
set to 0xffffffff. While this normally does not happen (since it
requires an uptime of possibly thousands of years, it may happen if the
TSC warps during S3).
If this looks sane, I'll sent it upstream.
Colin Ian King <email@example.com>