w1: w1_therm: use swap() to make code cleaner

Use the macro 'swap()' defined in 'include/linux/minmax.h' to avoid
opencoding it.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: David Yang <davidcomponentone@gmail.com>
Signed-off-by: Yang Guang <yang.guang5@zte.com.cn>
Link: https://lore.kernel.org/r/cb14f9e6e86cf8494ed2ddce6eec8ebd988908d9.1640077704.git.yang.guang5@zte.com.cn


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