usb: typec: tcpm: Fix misuses of AMS invocation

tcpm_ams_start is used to initiate an AMS as well as checking Collision
Avoidance conditions but not for flagging passive AMS (initiated by the
port partner). Fix the misuses of tcpm_ams_start in tcpm_pd_svdm.

ATTENTION doesn't need responses so the AMS flag is not needed here.

Fixes: 0bc3ee92 ("usb: typec: tcpm: Properly interrupt VDM AMS")
Signed-off-by: Kyle Tso <kyletso@google.com>
Link: https://lore.kernel.org/r/20210601123151.3441914-5-kyletso@google.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/tcpm.c

@@ -1555,7 +1555,7 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
 				svdm_version = PD_VDO_SVDM_VER(p[0]);
 			}
 
-			tcpm_ams_start(port, DISCOVER_IDENTITY);
+			port->ams = DISCOVER_IDENTITY;
 			/*
 			 * PD2.0 Spec 6.10.3: respond with NAK as DFP (data host)
 			 * PD3.1 Spec 6.4.4.2.5.1: respond with NAK if "invalid field" or
@@ -1576,19 +1576,18 @@ static int tcpm_pd_svdm(struct tcpm_port *port, struct typec_altmode *adev,
 			}
 			break;
 		case CMD_DISCOVER_SVID:
-			tcpm_ams_start(port, DISCOVER_SVIDS);
+			port->ams = DISCOVER_SVIDS;
 			break;
 		case CMD_DISCOVER_MODES:
-			tcpm_ams_start(port, DISCOVER_MODES);
+			port->ams = DISCOVER_MODES;
 			break;
 		case CMD_ENTER_MODE:
-			tcpm_ams_start(port, DFP_TO_UFP_ENTER_MODE);
+			port->ams = DFP_TO_UFP_ENTER_MODE;
 			break;
 		case CMD_EXIT_MODE:
-			tcpm_ams_start(port, DFP_TO_UFP_EXIT_MODE);
+			port->ams = DFP_TO_UFP_EXIT_MODE;
 			break;
 		case CMD_ATTENTION:
-			tcpm_ams_start(port, ATTENTION);
 			/* Attention command does not have response */
 			*adev_action = ADEV_ATTENTION;
 			return 0;