sound: Add uclass operations for beeping

Some audio codecs such as Intel HDA do not need to use digital data to
play sounds, but instead have a way to emit beeps. Add this interface as
an option. If the beep interface is not supported, then the sound uclass
falls back to the I2S interface.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

arch/sandbox/include/asm/test.h

@@ -161,6 +161,22 @@ int sandbox_get_setup_called(struct udevice *dev);
  */
 int sandbox_get_sound_sum(struct udevice *dev);
 
+/**
+ * sandbox_set_allow_beep() - Set whether the 'beep' interface is supported
+ *
+ * @dev: Device to update
+ * @allow: true to allow the start_beep() method, false to disallow it
+ */
+void sandbox_set_allow_beep(struct udevice *dev, bool allow);
+
+/**
+ * sandbox_get_beep_frequency() - Get the frequency of the current beep
+ *
+ * @dev: Device to check
+ * @return frequency of beep, if there is an active beep, else 0
+ */
+int sandbox_get_beep_frequency(struct udevice *dev);
+
 /**
  * sandbox_get_pch_spi_protect() - Get the PCI SPI protection status
  *