Add support for AVR devices from the 0-series.

Add support for AVR devices from the 0-series.

	PR target/92545
	* config/avr/avr-arch.h (avr_mcu_t) <flash_pm_offset>: New field.
	* config/avr/avr-devices.c (avr_mcu_types): Adjust initializers.
	* config/avr/avr-mcus.def (AVR_MCU): Add respective field.
	* config/avr/specs.h (LINK_SPEC) <%(link_pm_base_address)>: Add.
	* config/avr/gen-avr-mmcu-specs.c (print_mcu)
	<*cpp, *cpp_mcu, *cpp_avrlibc, *link_pm_base_address>: Emit code
	for spec definitions.
	* doc/avr-mmcu.texi: Regenerate.

From-SVN: r278387