AVR: target/119355 - Fix ICE in pass avr-fuse-move / -mfuse-move.

AVR: target/119355 - Fix ICE in pass avr-fuse-move / -mfuse-move.

This ICE only occurred when the compiler is built with, say
CXXFLAGS='-Wp,-D_GLIBCXX_ASSERTIONS'.  The problem was that
a value from an illegal REGNO was read.  The value was not
used in these cases, but the access triggered an assertion
due to reading past std::array.

gcc/
	PR target/119355
	* config/avr/avr-passes.cc (memento_t::apply): Only
	read values[p.arg] when it is actually used.