m68k: handle TLS access with offset

This reinstates FINAL_PRESCAN_INSN, and the calls in handle_move_double,
so that access to TLS variables with offset are properly handled.

gcc:
	PR target/106282
	* config/m68k/m68k.h (FINAL_PRESCAN_INSN): Define.
	* config/m68k/m68k.cc (m68k_final_prescan_insn): Define.
	(handle_move_double): Call it before handle_movsi.
	* config/m68k/m68k-protos.h: Declare it.

gcc/testsuite:
	PR target/106282
	* gcc.target/m68k/tls-gd-off.c: New.
	* gcc.target/m68k/tls-ie-off.c: New.
	* gcc.target/m68k/tls-ld-off.c: New.
	* gcc.target/m68k/tls-ld-xtls-off.c: New.
	* gcc.target/m68k/tls-le-off.c: New.
	* gcc.target/m68k/tls-le-xtls-off.c: New.
	* gcc.target/m68k/tls-ld.c: Make pattern less strict.
	* gcc.target/m68k/tls-le.c: Likewise.