ARM: 6251/1: Make SPARSE_IRQ a hidden option

SPARSE_IRQ doesn't need to be a visible option, only those platforms
supporting that will select it.
Signed-off-by: NEric Miao <eric.miao@canonical.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/Kconfig

@@ -1287,8 +1287,7 @@ config HW_PERF_EVENTS
 	  disabled, perf events will use software events only.
 
 config SPARSE_IRQ
-	bool "Support sparse irq numbering"
-	depends on EXPERIMENTAL
+	def_bool n
 	help
 	  This enables support for sparse irqs. This is useful in general
 	  as most CPUs have a fairly sparse array of IRQ vectors, which
@@ -1296,8 +1295,6 @@ config SPARSE_IRQ
 	  number of off-chip IRQs will want to treat this as
 	  experimental until they have been independently verified.
 
-	  If you don't know what to do here, say N.
-
 source "mm/Kconfig"
 
 config FORCE_MAX_ZONEORDER