typo fixes: mecanism -> mechanism

Signed-off-by: Adrian Bunk <bunk@stusta.de>
diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 8c28eb0..a820b77 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -988,7 +988,7 @@
 }
 
 /*
- * Initialize memory allocation mecanism, parse "memory" nodes and
+ * Initialize memory allocation mechanism, parse "memory" nodes and
  * obtain that way the top of memory and RMO to setup out local allocator
  */
 static void __init prom_init_mem(void)