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

Grammatical corrections to comments.

Signed-off-by: Linas Vepstas <linas@austin.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 6018178..3089eae 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -181,9 +181,9 @@
  	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));