RISC-V: Make rv32i_zcmp testcase more robust

RISC-V: Make rv32i_zcmp testcase more robust

GCC recently changed its register allocator which causes this
testcase to fail.
This patch updates the regex to be more robust to change by accepting
any s register in the range of 1-9 for cm.push and cm.popret insns.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rv32i_zcmp.c: Accept any register in the
	range of 1-9 for cm.push and cm.popret insns.

Signed-off-by: Patrick O'Neill <patrick@rivosinc.com>