Some parts don't define signature bytes

[stefanrueger]

The following mcus don't seem to define signature bytes.

  at43usb320
  at43usb355
  at76c711
  at90c8534
  at90pwm1
  at90pwm2
  at90pwm3
  at90s2333
  at90usb82
  at94k
  atmega32hvbrevb
  atmega8hva
  m3000

Some of these can be sourced as follows:

  at90pwm1   => [0x1E, 0x93, 0x83], # [1]
  at90pwm2   => [0x1E, 0x93, 0x81], # /usr/local/etc/avrdude.conf 9935     
  at90pwm3   => [0x1E, 0x93, 0x81], # /usr/local/etc/avrdude.conf 10118   
  at90s2333  => [0x1E, 0x91, 0x05], # /usr/local/etc/avrdude.conf 2331     
  at90usb82  => [0x1E, 0x93, 0x82], # /usr/local/etc/avrdude.conf 13273
  atmega8hva => [0x1E, 0x93, 0x10], # [2]

[1] Datasheet AT90PWM1
[2] Datasheet ATmega8HVA

[stefanrueger]

And, also

atmega32hvbrevb => [0x1E, 0x94, 0x0D], # [1]
atmega8hva      => [0x1E, 0x93, 0x10], # [1] in correspondence with the data sheet

[1] from Atmel-Studio's .atdf file in the corresponding DFP pack

It's possible (likely?) that the iom file for parts with missing signatures have other deficiencies, too. For example, the ATmega32HVBrevB has SPM_PAGESIZE defined as 64, but the .atdf file file thinks it's 128. And gcc-avr ought to #define __AVR_ATmega32HVBrevB__ rather than __AVR_ATmega32HVBREVB__.