ZTS: fix io_uring test on RHEL 9 variants (#16411)

Simplify the test, by using the variable "$PLATFORM_ID" in favor
of "$REDHAT_SUPPORT_PRODUCT_VERSION".

Signed-off-by: Tino Reichardt <[email protected]>
Reviewed-by: Tony Hutter <[email protected]>
Reviewed-by: George Melikov <[email protected]>

Author: mcmilk

tests/zfs-tests/tests/functional/io/io_uring.ksh

@@ -41,13 +41,13 @@ verify_runnable "global"
 
 
 if ! $(grep -q "CONFIG_IO_URING=y" /boot/config-$(uname -r)); then
-	log_unsupported "Requires io_uring support"
+	log_unsupported "Requires io_uring support within Kernel"
 fi
 
 if [ -e /etc/os-release ] ; then
 	source /etc/os-release
-	if [ -n "$REDHAT_SUPPORT_PRODUCT_VERSION" ] && ((floor($REDHAT_SUPPORT_PRODUCT_VERSION) == 9)) ; then
-		log_unsupported "Disabled on CentOS 9, fails with 'Operation not permitted'"
+	if [ $PLATFORM_ID = "platform:el9" ]; then
+		log_unsupported "Disabled on RHEL 9 variants: fails with 'Operation not permitted'"
 	fi
 fi