ARM: mmp: select specific CPU implementation

The behavior of the MMP platform code depends on whether the
CPU_PXA168/CPU_PXA910/CPU_MMP2 symbols are enabled or not.

I believe the intention here was that these can be left disabled for
a pure DT-only build, but it's not clear if that actually works. At
the minimum, the cpu_is_pxa168() and cpu_is_pxa910() checks behave
differently, which causes changes in the power management code.

For the moment, make the behavior depend on whether CONFIG_ATAGS is set
or not, to make it easier to bisect the removal of the old code later.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/mach-mmp/Kconfig

@@ -113,6 +113,8 @@ config MACH_MMP_DT
 	select PINCTRL_SINGLE
 	select ARCH_HAS_RESET_CONTROLLER
 	select CPU_MOHAWK
+	select CPU_PXA168 if ATAGS
+	select CPU_PXA910 if ATAGS
 	help
 	  Include support for Marvell MMP2 based platforms using
 	  the device tree. Needn't select any other machine while
@@ -125,6 +127,7 @@ config MACH_MMP2_DT
 	select PINCTRL_SINGLE
 	select ARCH_HAS_RESET_CONTROLLER
 	select CPU_PJ4
+	select CPU_MMP2 if ATAGS
 	select PM_GENERIC_DOMAINS if PM
 	select PM_GENERIC_DOMAINS_OF if PM && OF
 	help