CI: rename REV parameter to IRIS_REV for iris.dev builds

1 job for master in 8 minutes and 16 seconds (queued for 9 minutes and 50 seconds)
Status Job ID Name Coverage
  Test
failed #4623
fp-timing
build-iris.dev

00:08:16

 
Name Stage Failure
failed
build-iris.dev Test There is an unknown failure, please try again
make[1]: Target 'all' not remade because of errors.
make[1]: Leaving directory '/builds/FP/iris-atomic'
Makefile:6: recipe for target 'all' failed
make: *** [all] Error 2

real 0m4.858s
user 0m9.530s
sys 0m0.913s
ERROR: Job failed: exit code 1