[RISC-V] Correct CFA notes for stack-clash protection [PR120714]

[RISC-V] Correct CFA notes for stack-clash protection [PR120714]

Fixes incorrect SP-addresses used in CFA notes for the stack probes
unrelative to the frame's top. It applied to the RISC-V targets code
generation when the stack-clash protection is enabled.

	PR target/120714
gcc/ChangeLog:

	* config/riscv/riscv.cc (riscv_allocate_and_probe_stack_space):
	Fix SP-addresses in REG_CFA_DEF_CFA notes for stack-clash case.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/pr120714.c: New test.