[ci] Move CW340 job to CW340 board in default pool

We can now select FPGAs by their demands from a single pool rather than
splitting them across two pools.

Needed because the CW340 in the default pool is in the hyperdebug config
while the one in `FPGA CW340` is still in the SAM3X config and we can't
remove it without breaking in-flight pull requests.

Signed-off-by: James Wainwright <james.wainwright@lowrisc.org>
(cherry picked from commit 5cf1a37)

Author: jwnrt

azure-pipelines.yml

@@ -592,7 +592,9 @@ jobs:
 
 - job: execute_rom_fpga_tests_cw340
   displayName: CW340 ROM Tests
-  pool: FPGA CW340
+  pool:
+    name: $(fpga_pool)
+    demands: BOARD -equals cw340
   timeoutInMinutes: 60
   dependsOn:
     - chip_earlgrey_cw340