decode-dimms: Fix DDR3 extended temp range refresh rate decoding

Based on a patch from Peter Missel. The meaning of byte 31, bit 1,
was inverted. Also, this bit is only meaningful if the extended
temperature range is supported (bit 0 is set.)


git-svn-id: http://lm-sensors.org/svn/i2c-tools/trunk@6249 7894878c-1315-0410-8ee3-d5d059ff63e0