hwmon: (dme1737) demacrofy for readability

This patch gets rid of a couple of macros previously used for sysfs attribute
generation and manipulation. This makes the source a little bigger but a lot
more readable and maintainable. It also fixes an issue with pwm5 & pwm6
attributes not being created read-only initially.

Signed-Off-By: Juerg Haefliger <juergh at gmail.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>