thermal:ti-soc-thermal: Remove duplicate include in ti-bandgap

'of_device.h' included in 'ti-bandgap.c' is duplicated.
It is also included in the 25th line.

Signed-off-by: Zhang Yunkai <zhang.yunkai@zte.com.cn>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210306123415.219441-1-zhang.yunkai@zte.com.cn