tools: fw-update: allow ISO 8610 date formats

Currently, the ReleaseDateTime data is expected to be in a
"%d/%m/%Y %H:%M:%S" format.

However, this is ambiguous (ie., is locale-specific).

This change adds supoort to allow an ISO 8601 format of:

 "%Y-%m-%dT%H:%M:%S"

and a relaxed version with the 'T' separator replaced with a space:

 "%Y-%m-%d %H:%M:%S"

Update the readme and example json to switch to the preferred format.

Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Change-Id: Ica3ae824979df6b666b8abb619ceaedffd90b374
diff --git a/tools/fw-update/pldm_fwup_pkg_creator.py b/tools/fw-update/pldm_fwup_pkg_creator.py
index 0209f1a..b61afa5 100755
--- a/tools/fw-update/pldm_fwup_pkg_creator.py
+++ b/tools/fw-update/pldm_fwup_pkg_creator.py
@@ -186,9 +186,22 @@
     )
 
     if release_date_time_str is not None:
-        release_date_time = datetime.strptime(
-            release_date_time_str, "%d/%m/%Y %H:%M:%S"
-        )
+        formats = [
+            "%Y-%m-%dT%H:%M:%S",
+            "%Y-%m-%d %H:%M:%S",
+            "%d/%m/%Y %H:%M:%S",
+        ]
+        release_date_time = None
+        for fmt in formats:
+            try:
+                release_date_time = datetime.strptime(
+                    release_date_time_str, fmt
+                )
+                break
+            except ValueError:
+                pass
+        if release_date_time is None:
+            sys.exit("Can't parse release date '%s'" % release_date_time_str)
     else:
         release_date_time = datetime.now()