refactor(sgi): move apis and types to "nrd" prefix

Currently, functions and types internal to "neoverse_rd" platforms are
named with "sgi" as the prefix. Since common code and platforms are no
longer under the "sgi" umbrella, move the prefix to "nrd". This change
would amend the prefixes for functions, types and objects.

Signed-off-by: Rohit Mathew <Rohit.Mathew@arm.com>
Change-Id: I706a82bddf55c3be7cf9cef9aaa5df6d420098ca
diff --git a/plat/arm/board/neoverse_rd/platform/rdn2/include/rdn2_ras.h b/plat/arm/board/neoverse_rd/platform/rdn2/include/rdn2_ras.h
index 7a97ea3..c8a6f2d 100644
--- a/plat/arm/board/neoverse_rd/platform/rdn2/include/rdn2_ras.h
+++ b/plat/arm/board/neoverse_rd/platform/rdn2/include/rdn2_ras.h
@@ -9,6 +9,6 @@
 
 #include <nrd_ras.h>
 
-extern struct plat_sgi_ras_config ras_config;
+extern struct plat_nrd_ras_config ras_config;
 
 #endif /* RDN2_RAS_H */