resources: Update the riscv-ubuntu.img md5 hash and url

This resource has been updated:
https://gem5-review.googlesource.com/c/public/gem5-resources/+/57511

As such, the URL and the md5 value have been updated.

Change-Id: If557af207890ac953d68bdff92f818c22458dad1
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-resources/+/58009
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: Bobby Bruce <bbruce@ucdavis.edu>
diff --git a/resources.json b/resources.json
index f560b96..02a39c1 100644
--- a/resources.json
+++ b/resources.json
@@ -101,8 +101,8 @@
             "documentation" : "A disk image containing Ubuntu 20.04 for RISCV which will run an `m5 readfile` instruction after booting. If no script file is specified an `m5 exit` instruction will be exected",
             "architecture" : "RISCV",
             "is_zipped" : true,
-            "md5sum" : "b017372639ba13ad9ee9d9283647fa20",
-            "url" : "{url_base}/images/riscv/ubuntu-20-04/riscv-ubuntu.img.gz",
+            "md5sum" : "fece1414df7fa534a837e460095a9be8",
+            "url" : "{url_base}/images/riscv/ubuntu-20-04/riscv-ubuntu-20220318.img.gz",
             "source" : "src/riscv-ubuntu",
             "additional_metadata" : {
                 "root_partition": "1"
diff --git a/src/riscv-ubuntu/README.md b/src/riscv-ubuntu/README.md
index 205489d..bb37126 100644
--- a/src/riscv-ubuntu/README.md
+++ b/src/riscv-ubuntu/README.md
@@ -198,7 +198,7 @@
 
 # Pre-built disk image
 
-A pre-build, gzipped, disk image is available at <http://dist.gem5.org/dist/v21-2/images/riscv/ubuntu-20-04/riscv-ubuntu.img.gz>. **Note**: The password set for the `ubuntu` user is `helloworld`.
+A pre-build, gzipped, disk image is available at <http://dist.gem5.org/dist/v21-2/images/riscv/ubuntu-20-04/riscv-ubuntu-20220318.img.gz>. **Note**: The password set for the `ubuntu` user is `helloworld`.
 
 # Using the Disk Image
 This disk image is used in the following gem5 example RISCV config files, found within the gem5 repository: