target/riscv/program.c: fix clang warning

- I'm not sure I understand the logic behind the original statement,
but on macOS it fails to compile.

src/target/riscv/program.c

@@ -478,7 +478,11 @@ riscv_addr_t riscv_program_gah(struct riscv_program *p, riscv_addr_t addr)
 
 riscv_addr_t riscv_program_gal(struct riscv_program *p, riscv_addr_t addr)
 {
-	return ((addr > 0) ? 1 : 0) * (addr & 0x7FF);
+	if (addr > 0) {
+	    return (addr & 0x7FF);
+	} else {
+	    return 0;
+	}
 }
 
 int riscv_program_lah(struct riscv_program *p, enum gdb_regno d, riscv_addr_t addr)