ARM: exynos: enable multiplatform support

This makes it possible to enable the exynos platform as part of a
multiplatform kernel, in addition to keeping the single-platform
exynos support.

The multiplatform variant has a number of limitations at the moment:

* It only supports DT-enabled machines. This is not a problem in
  the long run, as non-DT machines for exynos are going away.
  The main problem here is that the gpio code and the exynos_eint
  irqchip are not multiplatform capable but still required for
  ATAGS based boot.
* The watchdog driver is still missing a conversion.
* sparsemem and memory_holes are currently not supported in
  multiplatform.

The the multiplatform aware ARCH_EXYNOS Kconfig symbol is disabled
for now, as dependent patches are still pending in other
subsystem trees. We will enable it once everything comes together.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
diff --git a/arch/arm/mach-exynos/common.c b/arch/arm/mach-exynos/common.c
index d63d399..83bd3f0 100644
--- a/arch/arm/mach-exynos/common.c
+++ b/arch/arm/mach-exynos/common.c
@@ -368,6 +368,9 @@
 	else
 		iotable_init(exynos4_iodesc1, ARRAY_SIZE(exynos4_iodesc1));
 
+	if (!IS_ENABLED(CONFIG_EXYNOS_ATAGS))
+		return
+
 	/* initialize device information early */
 	exynos4_default_sdhci0();
 	exynos4_default_sdhci1();
@@ -570,6 +573,8 @@
 	s3c24xx_init_uartdevs("exynos4210-uart", exynos4_uart_resources, cfg, no);
 }
 
+
+#ifdef CONFIG_EXYNOS_ATAGS
 static void __iomem *exynos_eint_base;
 
 static DEFINE_SPINLOCK(eint_lock);
@@ -875,3 +880,4 @@
 	return 0;
 }
 arch_initcall(exynos_init_irq_eint);
+#endif