ARM: spear: clean up editing mistake

Clean up an obvious editing mistake introduced by commit 4b6effb6ff38
("ARM: spear: merge Kconfig files").

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

arch/arm/mach-spear/Kconfig

@@ -92,7 +92,7 @@ config MACH_SPEAR600
 	depends on ARCH_SPEAR6XX
 	select USE_OF
 	help
-	  Supports ST SPEAr600 boards configured via the device-treesource "arch/arm/mach-spear6xx/Kconfig"
+	  Supports ST SPEAr600 boards configured via the device-tree
 
 config ARCH_SPEAR_AUTO
 	def_bool PLAT_SPEAR_SINGLE