* config/avr/avr.h (AVR_HAVE_8BIT_SP): New macros.
* config/avr/avr.c (avr_override_options): Initialize
avr_current_arch variable.
(avr_cpu_cpp_builtins): Define __AVR_HAVE_8BIT_SP__ or
__AVR_HAVE_16BIT_SP__ according to the device type.
(expand_prologue, output_movhi): Use AVR_HAVE_8BIT_SP instead of
TARGET_TINY_STACK.
(expand_epilogue): Use correct QI mode frame pointer for tiny stack.
Use AVR_HAVE_8BIT_SP instead of TARGET_TINY_STACK.