- Bugfixes:
   * internal osc: it's *12* MHz (not 15 MHz) on _current_ chips
      + except new Tempest parts where it's 16 MHz (and calibrated!)
      + or some old Sandstorm ones, where 15 MHz was valid
   * crystal config:
      + read and use the crystal config, don't assume 6 MHz
      + know when that field is 4 bits vs 5
   * an RCC2 register may be overriding the original RCC
      + more clock source options
      + bigger dividers
      + fractional dividers on Tempest (NYET handled)
   * there's a 30 KHz osc on newer chips (for deep sleep)
   * there's a 32768 Hz osc on newer chips (for hibernation)

 - Cosmetic
   * say "rev A0" not "vA.0", to match vendor docs
   * don't always report master clock as an "estimate":
      + give the error bound if it's approximate, like "±30%"
      + else don't say anything
   * fix whitespace and caps in some messages
   * these are not AT91SAM chips!!

Those clock issues might explain problems sometimes reported when
writing to Stellaris flash banks; they affect write timings.

That 12-vs-15 MHz issue is problematic; there's no consolidated doc
showing which chips (and revs!) have which internal oscillator speed.
It's clear that only older silicon had the faster-and-less-accurate
flavor.  What's less clear is which chips are "old" like that.

Lightly tested, on a DustDevil part.

git-svn-id: svn://svn.berlios.de/openocd/trunk@2626 b42882b7-edfa-0310-969c-e2dbd0fdcd60