Merge pull request #694 from g-oikonomou/contrib/gpio/with-ports

arch/cpu/cc2538/cc2538-def.h

arch/cpu/cc2538/dev/gpio-hal-arch.c

arch/cpu/cc2538/dev/gpio-hal-arch.h

arch/cpu/cc26x0-cc13x0/cc13xx-cc26xx-def.h

arch/cpu/cc26x0-cc13x0/dev/gpio-hal-arch.c

arch/cpu/cc26x0-cc13x0/dev/gpio-hal-arch.h

arch/cpu/native/dev/gpio-hal-arch.c

arch/cpu/native/native-def.h

arch/cpu/simplelink-cc13xx-cc26xx/cc13xx-cc26xx-conf.h

arch/cpu/simplelink-cc13xx-cc26xx/cc13xx-cc26xx-def.h

arch/cpu/simplelink-cc13xx-cc26xx/dev/gpio-hal-arch.c

arch/cpu/simplelink-cc13xx-cc26xx/dev/gpio-hal-arch.h

arch/dev/ext-flash/ext-flash.c

arch/platform/simplelink/cc13xx-cc26xx/srf06/als-sensor.c

examples/dev/gpio-hal/README.md

examples/dev/gpio-hal/gpio-hal-example.c

os/dev/button-hal.c

os/dev/button-hal.h

os/dev/gpio-hal.c

os/dev/gpio-hal.h