Flexnetwork 7503 (#1358)

* added hpe flexnetwork 7503

* updated specifications URL

device-types/HPE/FlexNetwork-7503.yaml

@@ -0,0 +1,30 @@
+---
+manufacturer: HPE
+model: FlexNetwork 7503
+slug: hpe-flexnetwork-7503
+part_number: JD240C
+u_height: 10
+is_full_depth: false
+weight: 66.68
+weight_unit: kg
+comments: '[HPE FlexNetwork 7500 Switch Series](https://support.hpe.com/hpesc/public/docDisplay?docId=c02707329&page=GUID-2F0420C4-474D-46DF-BC8C-A4A4C92C7714.html)'
+console-ports:
+  - name: Serial
+    type: de-9
+  - name: out-of-band
+    type: de-9
+module-bays:
+  - name: Switch Fabric Module 1
+    position: '0'
+  - name: Switch Fabric Module 2
+    position: '1'
+  - name: I/O Module 1
+    position: '2'
+  - name: I/O Module 2
+    position: '3'
+  - name: I/O Module 3
+    position: '4'
+  - name: PSU1
+    position: PSU1
+  - name: PSU2
+    position: PSU2