ARM: versatile: fix versatile_defconfig

With the introduction of CONFIG_ARCH_MULTIPLATFORM, versatile is no longer the default platform, so we need to enable CONFIG_ARCH_VERSATILE explicitly in order for that to be selected rather than the multiplatform configuration.

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I've applied this to the arm-soc fixes branch, since it seems obvious and uncontroversial. I only noticed because of another unrelated bug.

index cdd4d2b..2ba9e63 100644
@@ -1,3 +1,4 @@
+CONFIG_ARCH_VERSATILE=y
 CONFIG_EXPERIMENTAL=y
 # CONFIG_LOCALVERSION_AUTO is not set
 CONFIG_SYSVIPC=y