refactor(sgi): update comment references to "sgi platform"

As part of the move from "sgi", rename all comments referencing "sgi
platform" to "Neoverse RD platform".

Signed-off-by: Rohit Mathew <Rohit.Mathew@arm.com>
Change-Id: Ic72d6080cc74baaf40510e04d56926cdb5712311
diff --git a/expect/linux-busybox-nrd.exp b/expect/linux-busybox-nrd.exp
index b95a91f..0e527c0 100644
--- a/expect/linux-busybox-nrd.exp
+++ b/expect/linux-busybox-nrd.exp
@@ -4,7 +4,7 @@
 #
 # SPDX-License-Identifier: BSD-3-Clause
 #
-# Expect script for Linux boot process with RAM Disk for sgi platform
+# Expect script for Linux boot process with RAM Disk for Neovese RD platform.
 #
 # Refer to handle-arguments.inc for the list of parameters.
 #