Validate the tuner type index before accessing the tuner name table.
The previous check allowed an index equal to names.size(), which could
result in an out-of-range QStringList access.
Use a local integer value for the enum conversion and ensure only valid
indices are used when looking up tuner names.
pointed out by cppcheck: Access out of bounds
Signed-off-by: Robin Getz <rgetz503@gmail.com>