audio: solve 32bit system hdmi in mute issue [1/1]

PD#SWPL-813

Problem:
audio_iomap read audin reg 2800 error

Solution:
register val read from aml_read_cbus
maybe not positive number in 32bit system,
so change *val == -1 to judge mistake.

Verify:
verified by p321

Change-Id: Ie87001fa1daa621cadc2ce329d8dd863f39dcdb6
Signed-off-by: Lianlian Zhu <lianlian.zhu@amlogic.com>

sound/soc/amlogic/meson/audio_iomap.c

@@ -52,7 +52,7 @@ static int aml_snd_read(u32 base_type, unsigned int reg, int *val)
 		ret = -1;
 	} else {
 		*val = aml_read_cbus(reg);
-		if (*val < 0) {
+		if (*val == -1) {
 			pr_err("read cbus reg %x error\n", reg);
 			return -1;
 		}