middle-end/108086 - remove PR28238 fix superseeded by PR34018 fix

middle-end/108086 - remove PR28238 fix superseeded by PR34018 fix

There's quite special code in copy_bb that handles inline substitution
of a non-invariant address in place of an invariant one that's
now handled by more generic handling of this case in remap_gimple_op_r
so this removes the special casing that happens in a hot path, providing
a small speedup.

	PR middle-end/108086
	* tree-inline.cc (copy_bb): Remove handling of (foo *)&this->m
	substitution which is done in remap_gimple_op_r via
	re-gimplifying.