added EXTI

Signed-off-by: Tolga HOŞGÖR <fasdfasdas@gmail.com>
various EXTI RCC SYSCFG progress

Signed-off-by: Tolga HOŞGÖR <fasdfasdas@gmail.com>
various EXTI RCC SYSCFG progress and heavy syntax refactoring

Signed-off-by: Tolga HOŞGÖR <fasdfasdas@gmail.com>