fixup: avrxmega-hal: Add critical section-impl feature

Fixup for commit 978f2df

Author: agausmann

mcu/avrxmega-hal/Cargo.toml

@@ -8,6 +8,9 @@ rt = ["avr-device/rt"]
 device-selected = []
 attiny404 = ["avr-device/attiny404", "device-selected"]
 
+critical-section-impl = ["avr-device/critical-section-impl"]
+
+
 # Allow certain downstream crates to overwrite the device selection error by themselves.
 disable-device-selection-error = []