Add new purpose to the HAL layer.

Test: There will be a CTS test CL.
Change-Id: Ic623b7be8949fe0adb3706958a9be59f267057c4

include/hardware/keymaster_defs.h

@@ -279,6 +279,7 @@ typedef enum {
     KM_PURPOSE_SIGN = 2,       /* Usable with RSA, EC and HMAC keys. */
     KM_PURPOSE_VERIFY = 3,     /* Usable with RSA, EC and HMAC keys. */
     KM_PURPOSE_DERIVE_KEY = 4, /* Usable with EC keys. */
+    KM_PURPOSE_WRAP_KEY = 5,   /* Usable with wrapping keys. */
 } keymaster_purpose_t;
 
 typedef struct {