arm: pxa: fix pxa27x device-tree support kconfig

Remove the useless CPU_PXA27x non existing kconfig option.
The true options is PXA27x, which is already selected.
Reported-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>

arch/arm/mach-pxa/Kconfig

@@ -6,7 +6,6 @@ comment "Intel/Marvell Dev Platforms (sorted by hardware release time)"
 
 config MACH_PXA27X_DT
 	bool "Support PXA27x platforms from device tree"
-	select CPU_PXA27x
 	select POWER_SUPPLY
 	select PXA27x
 	select USE_OF