Digi customized linux kernel gpio.h file to allow debounce functionality by the
user space through the character device.
This commit patches the default gpio.h file that is used to generate the SDK
(which comes from kernel 4.18) with Digi debounce additions.
https://jira.digi.com/browse/DEL-7027
Signed-off-by: Hector Bujanda <hector.bujanda@digi.com>