staging: greybus: loopback_test: fix poll-mask build breakage

A scripted conversion from userland POLL* to kernel EPOLL* constants
mistakingly replaced the poll flags in the loopback_test tool, which
therefore no longer builds.

Fixes: a9a0884 ("vfs: do bulk POLL* -> EPOLL* replacement")
Cc: stable <stable@vger.kernel.org>     # 4.16
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20200312110151.22028-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/greybus/tools/loopback_test.c

@@ -655,7 +655,7 @@ static int open_poll_files(struct loopback_test *t)
 			goto err;
 		}
 		read(t->fds[fds_idx].fd, &dummy, 1);
-		t->fds[fds_idx].events = EPOLLERR|EPOLLPRI;
+		t->fds[fds_idx].events = POLLERR | POLLPRI;
 		t->fds[fds_idx].revents = 0;
 		fds_idx++;
 	}
@@ -748,7 +748,7 @@ static int wait_for_complete(struct loopback_test *t)
 		}
 
 		for (i = 0; i < t->poll_count; i++) {
-			if (t->fds[i].revents & EPOLLPRI) {
+			if (t->fds[i].revents & POLLPRI) {
 				/* Dummy read to clear the event */
 				read(t->fds[i].fd, &dummy, 1);
 				number_of_events++;