misc: ti-st: make st_recv() conforming to tty_ldisc_ops::receive_buf()

That is change data type to u8 and count to unsigned int. And propagate
to both hooks (st_kim_recv() and kim_int_recv()).

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20230810091510.13006-19-jirislaby@kernel.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>