USB: serial: io_ti: fix div-by-zero in set_termios

USB: serial: io_ti: fix div-by-zero in set_termios

[ Upstream commit 6aeb75e6adfaed16e58780309613a578fe1ee90b ]

Fix a division-by-zero in set_termios when debugging is enabled and a
high-enough speed has been requested so that the divisor value becomes
zero.

Instead of just fixing the offending debug statement, cap the baud rate
at the base as a zero divisor value also appears to crash the firmware.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>     # 2.6.12
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Orabug: 29487834
CVE: CVE-2017-18360
(cherry picked from commit 2cd394cd10465fc0878958ba99e6080ac8ead559)
Signed-off-by: Dan Duval <dan.duval@oracle.com>
Reviewed-by: Brian Maly <brian.maly@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>