Documentation/ABI: Correct mlxreg-io KernelVersion for 5.0

The mlxreg-io for the merge window assumed 4.21 as the next kernel
version. Replace 4.21 with 5.0.
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

Documentation/ABI/stable/sysfs-driver-mlxreg-io

@@ -24,7 +24,7 @@ What:		/sys/devices/platform/mlxplat/mlxreg-io/hwmon/hwmon*/
 							cpld3_version
 
 Date:		November 2018
-KernelVersion:	4.21
+KernelVersion:	5.0
 Contact:	Vadim Pasternak <vadimpmellanox.com>
 Description:	These files show with which CPLD versions have been burned
 		on LED board.
@@ -35,7 +35,7 @@ What:		/sys/devices/platform/mlxplat/mlxreg-io/hwmon/hwmon*/
 							jtag_enable
 
 Date:		November 2018
-KernelVersion:	4.21
+KernelVersion:	5.0
 Contact:	Vadim Pasternak <vadimpmellanox.com>
 Description:	These files enable and disable the access to the JTAG domain.
 		By default access to the JTAG domain is disabled.
@@ -105,7 +105,7 @@ What:		/sys/devices/platform/mlxplat/mlxreg-io/hwmon/hwmon*/
 						reset_voltmon_upgrade_fail
 
 Date:		November 2018
-KernelVersion:	4.21
+KernelVersion:	5.0
 Contact:	Vadim Pasternak <vadimpmellanox.com>
 Description:	These files show the system reset cause, as following: ComEx
 		power fail, reset from ComEx, system platform reset, reset