MLBEDSW-6613: Implement tile padding

Implement new padding mode which pads two edges of the IFM with the
current values of those edges

Signed-off-by: Rickard Bolin <rickard.bolin@arm.com>
Change-Id: I8523e0cabdac80b48710703859003e33050cc150
diff --git a/ethosu/vela/operation.py b/ethosu/vela/operation.py
index 54e823a..de68b1d 100644
--- a/ethosu/vela/operation.py
+++ b/ethosu/vela/operation.py
@@ -394,6 +394,7 @@
     SAME = 0
     VALID = 1
     EXPLICIT = 2  # Padding is specified in a PAD operation (only used for NPU operations)
+    TILE = 3  # Uses hardware tiles to pad by 1 with edge values on two sides of the IFM specified in explicit_padding
 
 
 class ActivationFunction: