tests/semaphore: fix "cpu test took too long" assertion failure

The SMP config for RISC-V on QEMU triggers this:

|START - test_sem_queue_mutual_exclusion
|
|Assertion failed at
| WEST_TOPDIR/zephyr/subsys/testsuite/ztest/src/ztest_new.c:155:
| cpu_hold: (dt < 3000 is false)
|1cpu test took too long (4090 ms)
|ERROR: cannot fail in test 'after()', bailing

Looping 10000 times is maybe a bit excessive.

Signed-off-by: Nicolas Pitre <[email protected]>

Author: Nicolas Pitre

tests/kernel/semaphore/semaphore/src/main.c

@@ -175,7 +175,7 @@ void sem_take_multiple_high_prio_helper(void *p1, void *p2, void *p3)
 /* First function for mutual exclusion test */
 void sem_queue_mutual_exclusion1(void *p1, void *p2, void *p3)
 {
-	for (int i = 0; i < 10000; i++) {
+	for (int i = 0; i < 1000; i++) {
 		expect_k_sem_take_nomsg(&mut_sem, K_FOREVER, 0);
 
 		/* in that function critical section makes critical var +1 */
@@ -194,7 +194,7 @@ void sem_queue_mutual_exclusion1(void *p1, void *p2, void *p3)
 /* Second function for mutual exclusion test */
 void sem_queue_mutual_exclusion2(void *p1, void *p2, void *p3)
 {
-	for (int i = 0; i < 10000; i++) {
+	for (int i = 0; i < 1000; i++) {
 		expect_k_sem_take_nomsg(&mut_sem, K_FOREVER, 0);
 
 		/* in that function critical section makes critical var 0 */