Testsuite: Fix a fail about xtheadcondmov-indirect-rv64.c

I find fail of the xtheadcondmov-indirect-rv64.c test case and provide a way to solve it.
In this patch, I take Kito's advice that I modify the form of the function bodies.It likes
*[a-x0-9].

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/xtheadcondmov-indirect-rv32.c: Generalize to be
	less sensitive to register allocation choices.
	* gcc.target/riscv/xtheadcondmov-indirect-rv64.c: Similarly.