Improve display_boot_progress() function

 - Remove out-dated information about the use of printf() in the
   function comment.

 - Make the argument const, as the function doesn't need to modify it.

 - Rename the function into bl1_print_bl31_ep_info() to make its
   purpose clearer.

Change-Id: I2a9d215a37f0ec11aefce0c5c9e050473b7a6b25
diff --git a/bl1/aarch64/bl1_exceptions.S b/bl1/aarch64/bl1_exceptions.S
index ef390d4..0bd0485 100644
--- a/bl1/aarch64/bl1_exceptions.S
+++ b/bl1/aarch64/bl1_exceptions.S
@@ -195,7 +195,7 @@
 	b.ne	unexpected_sync_exception
 
 	mov	x0, x20
-	bl	display_boot_progress
+	bl	bl1_print_bl31_ep_info
 
 	ldp	x0, x1, [x20, #ENTRY_POINT_INFO_PC_OFFSET]
 	msr	elr_el3, x0