Fix clippy warning (#86)

* Fix clippy improvements warnings

src/epd2in13bc/mod.rs

@@ -255,7 +255,7 @@ where
     ) -> Result<(), SPI::Error> {
         self.interface.cmd(spi, Command::DataStartTransmission1)?;
 
-        self.interface.data(spi, &buffer)?;
+        self.interface.data(spi, buffer)?;
 
         // Clear the chromatic layer
         let color = self.color.get_byte_value();

src/epd2in9bc/mod.rs

@@ -258,7 +258,7 @@ where
     ) -> Result<(), SPI::Error> {
         self.interface.cmd(spi, Command::DataStartTransmission1)?;
 
-        self.interface.data(spi, &buffer)?;
+        self.interface.data(spi, buffer)?;
 
         // Clear the chromatic layer
         let color = self.color.get_byte_value();

src/graphics.rs

@@ -300,7 +300,7 @@ impl<'a> OriginDimensions for VarDisplay<'a> {
 
 impl<'a> Display for VarDisplay<'a> {
     fn buffer(&self) -> &[u8] {
-        &self.buffer
+        self.buffer
     }
 
     fn get_mut_buffer(&mut self) -> &mut [u8] {