rtc: rtctest: Improve support detection

The rtc-generic and opal-rtc are failing to run this test as they do not
support all the features. Let's treat the error returns and skip to the
following test.

Theoretically the test_DATE should be also adjusted, but as it's enabled
on demand I think it makes sense to fail in such case.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

tools/testing/selftests/timers/rtctest.c

@@ -221,6 +221,11 @@ test_READ:
 	/* Read the current alarm settings */
 	retval = ioctl(fd, RTC_ALM_READ, &rtc_tm);
 	if (retval == -1) {
+		if (errno == EINVAL) {
+			fprintf(stderr,
+					"\n...EINVAL reading current alarm setting.\n");
+			goto test_PIE;
+		}
 		perror("RTC_ALM_READ ioctl");
 		exit(errno);
 	}
@@ -231,7 +236,7 @@ test_READ:
 	/* Enable alarm interrupts */
 	retval = ioctl(fd, RTC_AIE_ON, 0);
 	if (retval == -1) {
-		if (errno == EINVAL) {
+		if (errno == EINVAL || errno == EIO) {
 			fprintf(stderr,
 				"\n...Alarm IRQs not supported.\n");
 			goto test_PIE;