spl: do not repeat timer init on i.MX6

The GPT timer was already initialised in board_init_f() as
it is needed in dram init. Do not repeat timer init in
board_init_r().

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Acked-by: Stefano Babic <sbabic@denx.de>
diff --git a/common/spl/spl.c b/common/spl/spl.c
index d245cfc..8b219ba 100644
--- a/common/spl/spl.c
+++ b/common/spl/spl.c
@@ -379,7 +379,7 @@
 		if (spl_init())
 			hang();
 	}
-#ifndef CONFIG_PPC
+#if !defined(CONFIG_PPC) && !defined(CONFIG_ARCH_MX6)
 	/*
 	 * timer_init() does not exist on PPC systems. The timer is initialized
 	 * and enabled (decrementer) in interrupt_init() here.