chore(rdv3): rename platform RD-Fremont to RD-V3

Arm has decided to rename RD-Fremont to RD-V3 to align with its
existing product lineup, such as RD-V1, RD-V2, etc. This change
replaces all occurences of "Fremont" with "V3" in file names and
contents.

Change-Id: I302103492f962a7ac74854633ad68701b2a7f420
Signed-off-by: Jerry Wang <Jerry.Wang4@arm.com>
diff --git a/changelog.yaml b/changelog.yaml
index 6a235cd..5655603 100644
--- a/changelog.yaml
+++ b/changelog.yaml
@@ -241,8 +241,8 @@
               - title: RD-N2
                 scope: rdn2
 
-              - title: RD-Fremont
-                scope: rdfremont
+              - title: RD-V3
+                scope: rdv3
 
                 deprecated:
                   - board/rdn2