trivial: Style changed files

platsupport: Replace read/write w/ set/read_level

This is the second part of the change to remove the ability the chain
together pins in the driver level. Now that it's not possible to chain
together pins, we replace the read/write functions with pin unit level
functions.

platsupport: Remove GPIO set_next and next field

The functionality to be able to chain together GPIO pins is outside the
scope of the driver, this functionality should instead belong to a
utility library. This commit removes this from the drivers so that it
can be refactored into a library.

platsupport: Don't require plat/gpio.h on all plat

The Arm interface for gpio_sys_t doesn't require any platform
definitions and so we don't need to include a platform header file.

platsupport: use ZF_LOG* instead of custom macros

This commit removes redundant definitions of debug print macros
and replaces them with use of ZF_LOG*.

Fix whitespace

- remove trailing whitespace
- remove duplicate blank lines
- remove blank lines at end of file

fix licenses

Remove trailing whitespace