ASoC: Only write back non-default registers when resuming WM8753

This will reduce the number of writes done on resume, allowing that to
complete faster (especially on systems with very slow I2C like the
current Samsung driver).

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/codecs/wm8753.c

@@ -1526,6 +1526,11 @@ static int wm8753_resume(struct platform_device *pdev)
 	for (i = 0; i < ARRAY_SIZE(wm8753_reg); i++) {
 		if (i + 1 == WM8753_RESET)
 			continue;
+
+		/* No point in writing hardware default values back */
+		if (cache[i] == wm8753_reg[i])
+			continue;
+
 		data[0] = ((i + 1) << 1) | ((cache[i] >> 8) & 0x0001);
 		data[1] = cache[i] & 0x00ff;
 		codec->hw_write(codec->control_data, data, 2);