ARM: provide an early platform initialization hook

This allows platforms to hook into the initialization early to setup
things like scheduler clocks, etc.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/setup.c

@@ -880,6 +880,9 @@ void __init setup_arch(char **cmdline_p)
 #endif
 #endif
 	early_trap_init();
+
+	if (mdesc->init_early)
+		mdesc->init_early();
 }