ARM: drop experimental status of SMP_ON_UP

SMP_ON_UP has been around for a while, and seems to be well-proven now.
Drop the EXPERIMENTAL tag from the option.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig

@@ -1343,7 +1343,7 @@ config SMP
 	  If you don't know what to do here, say N.
 
 config SMP_ON_UP
-	bool "Allow booting SMP kernel on uniprocessor systems (EXPERIMENTAL)"
+	bool "Allow booting SMP kernel on uniprocessor systems"
 	depends on SMP && !XIP_KERNEL && MMU
 	default y
 	help