treewide: Remove critical-section-impl crate features

avr-device no longer has a `critical-section-impl` feature.  Instead it
now has a `critical-section` feature that is enabled by default [1].  As
such, we can drop the re-exposed feature here.

[1]: Rahix/avr-device#195

Author: Rahix

arduino-hal/Cargo.toml

@@ -14,8 +14,6 @@ categories = ["no-std", "embedded", "hardware-support"]
 default = ["rt"]
 rt = ["avr-device/rt"]
 
-critical-section-impl = ["avr-device/critical-section-impl"]
-
 board-selected = []
 mcu-atmega = []
 mcu-attiny = []

mcu/atmega-hal/Cargo.toml

@@ -29,8 +29,6 @@ atmega1284p = ["avr-device/atmega1284p", "device-selected"]
 atmega8 = ["avr-device/atmega8", "device-selected"]
 atmega88p = ["avr-device/atmega88p", "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 = []
 

mcu/attiny-hal/Cargo.toml

@@ -19,8 +19,6 @@ attiny88 = ["avr-device/attiny88", "device-selected"]
 attiny167 = ["avr-device/attiny167", "device-selected"]
 attiny2313 = ["avr-device/attiny2313", "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 = []