tools/nolibc/poll: use kernel types for system call invocations

tools/nolibc/poll: use kernel types for system call invocations

The system calls expect 'struct __kernel_old_timespec'.
While currently 'struct __kernel_old_timespec' and 'struct timespec' are
compatible, this is confusing. Especially as future patches will change
the definition of 'struct timespec'.

Use the correct kernel type instead.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/lkml/fbca1d3e-12e4-4c4e-8091-87464035fe39@app.fastmail.com/
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Willy Tarreau <w@1wt.eu>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20251220-nolibc-uapi-types-v3-1-c662992f75d7@weissschuh.net