middle-end: Revert can_special_div_by_const changes [PR108583]

This reverts the changes for the CAN_SPECIAL_DIV_BY_CONST hook.

gcc/ChangeLog:

	PR target/108583
	* doc/tm.texi (TARGET_VECTORIZE_CAN_SPECIAL_DIV_BY_CONST): Remove.
	* doc/tm.texi.in: Likewise.
	* explow.cc (round_push, align_dynamic_address): Revert previous patch.
	* expmed.cc (expand_divmod): Likewise.
	* expmed.h (expand_divmod): Likewise.
	* expr.cc (force_operand, expand_expr_divmod): Likewise.
	* optabs.cc (expand_doubleword_mod, expand_doubleword_divmod): Likewise.
	* target.def (can_special_div_by_const): Remove.
	* target.h: Remove tree-core.h include
	* targhooks.cc (default_can_special_div_by_const): Remove.
	* targhooks.h (default_can_special_div_by_const): Remove.
	* tree-vect-generic.cc (expand_vector_operation): Remove hook.
	* tree-vect-patterns.cc (vect_recog_divmod_pattern): Remove hook.
	* tree-vect-stmts.cc (vectorizable_operation): Remove hook.