Duplicated include guards HARDWARE_UTILS_H

[steph643]

The include guard HARDWARE_UTILS_H is present both in current_sense/hardware_api.h and drivers/hardware_api.h. This prevents compiling the project in certain specific setups (I found this while porting the library to another compiler).

Moreover, I would also rename the files. Having different files with the same name in a project looks error prone to me.