Extend POST support for PPC440

Added memory, CPU, UART, I2C and SPR POST tests for PPC440.

Signed-off-by: Igor Lisitsin <igor@emcraft.com>
--
diff --git a/post/post.c b/post/post.c
index ac41990..28435cc 100644
--- a/post/post.c
+++ b/post/post.c
@@ -428,7 +428,7 @@
 unsigned long post_time_ms (unsigned long base)
 {
 #ifdef CONFIG_PPC
-	return (unsigned long)get_ticks () / (get_tbclk () / CFG_HZ) - base;
+	return (unsigned long)(get_ticks () / (get_tbclk () / CFG_HZ)) - base;
 #else
 #warning "Not implemented yet"
 	return 0; /* Not implemented yet */