RISC-V: Fix regression of -fzero-call-used-regs=all [PR109104]

RISC-V: Fix regression of -fzero-call-used-regs=all [PR109104]

This patch registers a riscv specific function to
TARGET_ZERO_CALL_USED_REGS instead of default in targhooks.cc. It will
clean gpr and vector relevant registers.

gcc/ChangeLog:

	PR target/109104
	* config/riscv/riscv-protos.h (emit_hard_vlmax_vsetvl): New.
	* config/riscv/riscv-v.cc (emit_hard_vlmax_vsetvl): New.
	(emit_vlmax_vsetvl): Use emit_hard_vlmax_vsetvl.
	* config/riscv/riscv.cc (vector_zero_call_used_regs): New.
	(riscv_zero_call_used_regs): New.
	(TARGET_ZERO_CALL_USED_REGS): New.

gcc/testsuite/ChangeLog:

	PR target/109104
	* gcc.target/riscv/zero-scratch-regs-1.c: New test.
	* gcc.target/riscv/zero-scratch-regs-2.c: New test.
	* gcc.target/riscv/zero-scratch-regs-3.c: New test.

Signed-off-by: Yanzhang Wang <yanzhang.wang@intel.com>
Co-authored-by: Pan Li <pan2.li@intel.com>
Co-authored-by: Ju-Zhe Zhong <juzhe.zhong@rivai.ai>
Co-authored-by: Kito Cheng <kito.cheng@sifive.com>