use embedded_hal through stm32f4xx_hal instead of direct dependency

this will aid maintainability.

Cargo.lock

@@ -355,7 +355,6 @@ dependencies = [
  "cortex-m",
  "cortex-m-log",
  "cortex-m-rt",
- "embedded-hal",
  "hash2hwaddr",
  "log",
  "nom",

Cargo.toml

@@ -21,7 +21,6 @@ bare-metal = "0.2"
 cortex-m = "0.6"
 cortex-m-rt = { version = "0.6", features = ["device"] }
 cortex-m-log = { version = "0.6", features = ["log-integration"] }
-embedded-hal = "0.2"
 # TODO: pending https://github.com/stm32-rs/stm32f4xx-hal/pull/125
 stm32f4xx-hal = { git = "https://github.com/thalesfragoso/stm32f4xx-hal", branch = "pwm-impl", features = ["rt", "stm32f427"] }
 stm32-eth = { version = "0.1.2", features = ["smoltcp-phy"], git = "https://github.com/stm32-rs/stm32-eth.git" }

src/ad5680.rs

@@ -1,8 +1,8 @@
-use embedded_hal::{
+use stm32f4xx_hal::{
+    hal::{
         blocking::spi::Transfer,
         digital::v2::OutputPin,
-};
+    },
-use stm32f4xx_hal::{
     time::MegaHertz,
     spi,
 };

src/ad7172/adc.rs

@@ -1,7 +1,9 @@
 use core::fmt;
-use embedded_hal::digital::v2::OutputPin;
-use embedded_hal::blocking::spi::Transfer;
 use log::{info, warn};
+use stm32f4xx_hal::hal::{
+    blocking::spi::Transfer,
+    digital::v2::OutputPin,
+};
 use super::{
     regs::{self, Register, RegisterData},
     checksum::{ChecksumMode, Checksum},