olimexino_stm32: provide button and leds for basic samples

Provide BUT button and LED1, LED2 leds defines in order to get
basic samples "blinky" and "button" available on olimexino_stm32.
Defines have been named in order to match with board printing.
Aliases are provided to get compatibility with zephyr sample code.

Change-Id: I975dc6c043ea83935fb229cafc737cb3ed80fdc4
Signed-off-by: Yannis Damigos <giannis.damigos@gmail.com>