Documentation: qat: Use code block for qat sysfs example

kernel test robot and Stephen Rothwell reported htmldocs warning:

Documentation/ABI/testing/sysfs-driver-qat:24: WARNING: Unexpected indentation.

The warning isn't caused by Date: field pointed by the warning, but rather
by sysfs example that isn't in literal code block.

Add the code block marker.

Link: https://lore.kernel.org/linux-next/20220711204932.333379b4@canb.auug.org.au/
Link: https://lore.kernel.org/linux-doc/202207090803.TEGI95qw-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Fixes: d4cfb144f6 ("crypto: qat - expose device config through sysfs for 4xxx")
Acked-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Cc: Wojciech Ziemba <wojciech.ziemba@intel.com>
Cc: Adam Guerin <adam.guerin@intel.com>
Cc: Fiona Trahe <fiona.trahe@intel.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Vladis Dronov <vdronov@redhat.com>
Cc: Tomasz Kowallik <tomaszx.kowalik@intel.com>
Cc: linux-crypto@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Bagas Sanjaya <bagasdotme@gmail.com>
Acked-by: Vladis Dronov <vdronov@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Documentation/ABI/testing/sysfs-driver-qat

@@ -46,7 +46,8 @@ Description:	Reports the current configuration of the QAT device and allows
 
 		The following example shows how to change the configuration of
 		a device configured for running crypto services in order to
-		run data compression:
+		run data compression::
+
 			# cat /sys/bus/pci/devices/<BDF>/qat/state
 			up
 			# cat /sys/bus/pci/devices/<BDF>/qat/cfg_services