uart_ow: prevent possible infinite loop in _ow_read_byte()
uart_ow: prevent possible infinite loop in _ow_read_byte()

With a broken device, or a broken interface circuit, it is possible
for _ow_read_byte() to spin forever.  This patch arranges for it to
timeout after 5 seconds if it cannot read a valid byte from the UART.

Signed-off-by: Jon Trulson <08664b19c2d4086eb239dd8ec32d593676a5b9e4@ics.com>
Signed-off-by: Brendan Le Foll <3e0e8c4069934e8b47d99704927a85c66c0ceb33@intel.com>

malikabhi05/mraa,arunlee77/mraa,malikabhi05/mraa,g-vidal/mraa,spitfire88/mraa,alext-mkrs/mraa,jontrulson/mraa,KurtE/mraa,stefan-andritoiu/mraa,sergev/mraa,arunlee77/mraa,whbruce/mraa,sergev/mraa,arfoll/mraa,KurtE/mraa,intel-iot-devkit/mraa,stefan-andritoiu/mraa-gpio-chardev,sergev/mraa,Propanu/mraa,spitfire88/mraa,ncrastanaren/mraa,intel-iot-devkit/mraa,Jon-ICS/mraa,intel-iot-devkit/mraa,KurtE/mraa,stefan-andritoiu/mraa,malikabhi05/mraa,ncrastanaren/mraa,g-vidal/mraa,stefan-andritoiu/mraa-gpio-chardev,jontrulson/mraa,alext-mkrs/mraa,stefan-andritoiu/mraa,sergev/mraa,g-vidal/mraa,intel-iot-devkit/mraa,arfoll/mraa,alext-mkrs/mraa,arfoll/mraa,stefan-andritoiu/mraa-gpio-chardev,g-vidal/mraa,Propanu/mraa,yongli3/mraa,whbruce/mraa,arunlee77/mraa,Propanu/mraa,alext-mkrs/mraa,ncrastanaren/mraa,malikabhi05/mraa,yongli3/mraa,stefan-andritoiu/mraa-gpio-chardev,Jon-ICS/mraa,jontrulson/mraa,jontrulson/mraa,yongli3/mraa,whbruce/mraa,malikabhi05/mraa,Propanu/mraa,arfoll/mraa,yongli3/mraa,stefan-andritoiu/mraa,ncrastanaren/mraa,whbruce/mraa,KurtE/mraa,g-vidal/mraa,spitfire88/mraa,stefan-andritoiu/mraa-gpio-chardev,intel-iot-devkit/mraa,spitfire88/mraa,sergev/mraa,Jon-ICS/mraa,Propanu/mraa,KurtE/mraa,yongli3/mraa,arunlee77/mraa,arfoll/mraa,ncrastanaren/mraa,jontrulson/mraa,alext-mkrs/mraa,stefan-andritoiu/mraa