misc: amd-sbi: Optimize the wait condition for mailbox command completion

- optimize the wait condition to indicate command completion
  by replacing the do while loop with regmap subsystem API
  regmap_read_poll_timeout()

Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>
Link: https://lore.kernel.org/r/20250428063034.2145566-6-akshay.gupta@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: akky16

drivers/misc/amd-sbi/rmi-core.c

@@ -23,7 +23,7 @@ int rmi_mailbox_xfer(struct sbrmi_data *data,
 		     struct sbrmi_mailbox_msg *msg)
 {
 	unsigned int bytes;
-	int i, ret, retry = 10;
+	int i, ret;
 	int sw_status;
 	u8 byte;
 
@@ -64,21 +64,10 @@ int rmi_mailbox_xfer(struct sbrmi_data *data,
 	 * an ALERT (if enabled) to initiator (BMC) to indicate completion
 	 * of the requested command
 	 */
-	do {
-		ret = regmap_read(data->regmap, SBRMI_STATUS, &sw_status);
-		if (sw_status < 0) {
-			ret = sw_status;
-			goto exit_unlock;
-		}
-		if (sw_status & SW_ALERT_MASK)
-			break;
-		usleep_range(50, 100);
-	} while (retry--);
-
-	if (retry < 0) {
-		ret = -EIO;
+	ret = regmap_read_poll_timeout(data->regmap, SBRMI_STATUS, sw_status,
+				       sw_status & SW_ALERT_MASK, 500, 2000000);
+	if (ret)
 		goto exit_unlock;
-	}
 
 	/*
 	 * For a read operation, the initiator (BMC) reads the firmware