misc: amd-sbi: Explicitly clear in/out arg "mb_in_out"

- New AMD processor will support different input/output for same command.
- In some scenarios the input value is not cleared, which will be added to
  output before reporting the data.
- Clearing input explicitly will be a cleaner and safer approach.

Reviewed-by: Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
Signed-off-by: Akshay Gupta <akshay.gupta@amd.com>
Link: https://lore.kernel.org/r/20250716110729.2193725-3-akshay.gupta@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: akky16

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

@@ -320,6 +320,10 @@ int rmi_mailbox_xfer(struct sbrmi_data *data,
 	ret = regmap_read(data->regmap, SBRMI_OUTBNDMSG7, &ec);
 	if (ret || ec)
 		goto exit_clear_alert;
+
+	/* Clear the input value before updating the output data */
+	msg->mb_in_out = 0;
+
 	/*
 	 * For a read operation, the initiator (BMC) reads the firmware
 	 * response Command Data Out[31:0] from SBRMI::OutBndMsg_inst[4:1]