[POWERPC] setup_64.c and prom.c comment cleanup

Grammatical corrections to comments.
Signed-off-by: NLinas Vepstas <linas@austin.ibm.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>

arch/powerpc/kernel/prom.c

@@ -430,9 +430,11 @@ static int __init early_parse_mem(char *p)
 }
 early_param("mem", early_parse_mem);
 
-/*
- * The device tree may be allocated below our memory limit, or inside the
- * crash kernel region for kdump. If so, move it out now.
+/**
+ * move_device_tree - move tree to an unused area, if needed.
+ *
+ * The device tree may be allocated beyond our memory limit, or inside the
+ * crash kernel region for kdump. If so, move it out of the way.
  */
 static void move_device_tree(void)
 {

arch/powerpc/kernel/setup_64.c

@@ -181,9 +181,9 @@ void __init early_setup(unsigned long dt_ptr)
  	DBG(" -> early_setup(), dt_ptr: 0x%lx\n", dt_ptr);
 
 	/*
-	 * Do early initializations using the flattened device
-	 * tree, like retreiving the physical memory map or
-	 * calculating/retreiving the hash table size
+	 * Do early initialization using the flattened device
+	 * tree, such as retrieving the physical memory map or
+	 * calculating/retrieving the hash table size.
 	 */
 	early_init_devtree(__va(dt_ptr));