gpio/stm32: provide GPIO driver implementation for STM32F3X family

Implementation includes adding some defines in the pinmux,
adjusting gpio driver to specific defines for STM32F3X family,
adding specific functionality in the F3X SoC definition.

Change-Id: I465c66eb93e7afb43166c4585c852e284b0d6e67
Signed-off-by: Adam Podogrocki <adam.podogrocki@rndity.com>
11 files changed