usb: pd: Add captive Type C cable type

The USB Power Delivery Specification R3.0 adds a captive cable type
to the "USB Type-C plug to USB Type-C/Captive" field (Bits 19-18,
Passive/Active Cable VDO, Table 6-38 & 6-39).

Add the corresponding definition to the Cable VDO header. Also add a
helper macro to get the Type C cable connector type, when provided
the cable VDO.

Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Prashant Malani <pmalani@chromium.org>
Reviewed-by: Benson Leung <bleung@chromium.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20201116201150.2919178-2-pmalani@chromium.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/usb/pd_vdo.h

@@ -177,7 +177,7 @@
  * <31:28> :: Cable HW version
  * <27:24> :: Cable FW version
  * <23:20> :: Reserved, Shall be set to zero
- * <19:18> :: type-C to Type-A/B/C (00b == A, 01 == B, 10 == C)
+ * <19:18> :: type-C to Type-A/B/C/Captive (00b == A, 01 == B, 10 == C, 11 == Captive)
  * <17>    :: Type-C to Plug/Receptacle (0b == plug, 1b == receptacle)
  * <16:13> :: cable latency (0001 == <10ns(~1m length))
  * <12:11> :: cable termination type (11b == both ends active VCONN req)
@@ -193,6 +193,7 @@
 #define CABLE_ATYPE		0
 #define CABLE_BTYPE		1
 #define CABLE_CTYPE		2
+#define CABLE_CAPTIVE		3
 #define CABLE_PLUG		0
 #define CABLE_RECEPTACLE	1
 #define CABLE_CURR_1A5		0
@@ -208,6 +209,7 @@
 	 | (tx1d) << 10 | (tx2d) << 9 | (rx1d) << 8 | (rx2d) << 7	\
 	 | ((cur) & 0x3) << 5 | (vps) << 4 | (sopp) << 3		\
 	 | ((usbss) & 0x7))
+#define VDO_TYPEC_CABLE_TYPE(vdo)	(((vdo) >> 18) & 0x3)
 
 /*
  * AMA VDO