[Pal] Fix sign of a few PAL return values

Some PAL functions return positive error code accidentally.

Pal/src/host/Linux-SGX/db_sockets.c

@@ -150,7 +150,7 @@ static int inet_create_uri (char * uri, int count, struct sockaddr * addr,
 
     if (addr->sa_family == AF_INET) {
         if (addrlen != sizeof(struct sockaddr_in))
-            return PAL_ERROR_INVAL;
+            return -PAL_ERROR_INVAL;
 
         struct sockaddr_in * addr_in = (struct sockaddr_in *) addr;
         char * addr = (char *) &addr_in->sin_addr.s_addr;
@@ -164,7 +164,7 @@ static int inet_create_uri (char * uri, int count, struct sockaddr * addr,
                        __ntohs(addr_in->sin_port));
     } else if (addr->sa_family == AF_INET6) {
         if (addrlen != sizeof(struct sockaddr_in6))
-            return PAL_ERROR_INVAL;
+            return -PAL_ERROR_INVAL;
 
         struct sockaddr_in6 * addr_in6 = (struct sockaddr_in6 *) addr;
         unsigned short * addr = (unsigned short *) &addr_in6->sin6_addr.s6_addr;

Pal/src/host/Linux-SGX/sgx_graphene.c

@@ -51,7 +51,7 @@ int _DkEventSet (PAL_HANDLE event, int wakeup)
                              NULL, NULL, 0);
     }
 
-    return IS_ERR(ret) ? PAL_ERROR_TRYAGAIN : ret;
+    return IS_ERR(ret) ? -PAL_ERROR_TRYAGAIN : ret;
 }
 
 int _DkEventWait (PAL_HANDLE event)

Pal/src/host/Linux/db_events.c

@@ -72,7 +72,7 @@ int _DkEventSet (PAL_HANDLE event, int wakeup)
                              NULL, NULL, 0);
     }
 
-    return IS_ERR(ret) ? PAL_ERROR_TRYAGAIN : ret;
+    return IS_ERR(ret) ? -PAL_ERROR_TRYAGAIN : ret;
 }
 
 int _DkEventWaitTimeout (PAL_HANDLE event, uint64_t timeout)

Pal/src/host/Linux/db_sockets.c

@@ -157,7 +157,7 @@ static int inet_create_uri (char * uri, int count, struct sockaddr * addr,
 
     if (addr->sa_family == AF_INET) {
         if (addrlen != sizeof(struct sockaddr_in))
-            return PAL_ERROR_INVAL;
+            return -PAL_ERROR_INVAL;
 
         struct sockaddr_in * addr_in = (struct sockaddr_in *) addr;
         char * addr = (char *) &addr_in->sin_addr.s_addr;
@@ -171,7 +171,7 @@ static int inet_create_uri (char * uri, int count, struct sockaddr * addr,
                        __ntohs(addr_in->sin_port));
     } else if (addr->sa_family == AF_INET6) {
         if (addrlen != sizeof(struct sockaddr_in6))
-            return PAL_ERROR_INVAL;
+            return -PAL_ERROR_INVAL;
 
         struct sockaddr_in6 * addr_in6 = (struct sockaddr_in6 *) addr;
         unsigned short * addr = (unsigned short *) &addr_in6->sin6_addr.s6_addr;