tools/nolibc: use poll-related definitions from UAPI headers

The UAPI headers already provide definitions for these symbols.
Using them makes the code shorter, more robust and compatible with
applications using linux/poll.h directly.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20250430-poll-v1-2-44b5ceabdeee@linutronix.de
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

tools/include/nolibc/poll.h

@@ -11,9 +11,9 @@
 #define _NOLIBC_POLL_H
 
 #include "arch.h"
-#include "types.h"
 #include "sys.h"
 
+#include <linux/poll.h>
 #include <linux/time.h>
 
 /*

tools/include/nolibc/types.h

@@ -159,20 +159,6 @@ typedef struct {
 			__set->fds[__idx] = 0;				\
 	} while (0)
 
-/* for poll() */
-#define POLLIN          0x0001
-#define POLLPRI         0x0002
-#define POLLOUT         0x0004
-#define POLLERR         0x0008
-#define POLLHUP         0x0010
-#define POLLNVAL        0x0020
-
-struct pollfd {
-	int fd;
-	short int events;
-	short int revents;
-};
-
 /* for getdents64() */
 struct linux_dirent64 {
 	uint64_t       d_ino;