input: keyboard: cypress-touchkey: Some changes and code cleanup

- Use only one pointer to cypress_touchkey_devdata, instead of three
- Register the early suspend only when needed (CONFIG_HAS_EARLYSUSPEND)
- Removed unuseful code and commented code
- Code reindented for better readability
input: keyboard: cypress-touchkey: Customizable timeout for touchkeys backlight

This commit adds a sysfs customizable timeout parameter for the touchkeys backlight.
The parameter could be found at the following path:
/sys/class/misc/notification/bl_timeout
input: keyboard: cypress-touchkey: Manage the timeout of touchkeys backlight after a touchscreen press
input: keyboard: cypress-touchkey: Customizable activation status of touchkeys backlight on touchscreen press

This commit adds a sysfs customizable status parameter to enable/disable
the touchkeys backlight on a touchscreen press.
The parameter could be found at the following path:
/sys/class/misc/notification/touchlight_enabled