kinetis: GPIO: avoid dup calls to cortexm_isr_end on KW41Z
kinetis: GPIO: avoid dup calls to cortexm_isr_end on KW41Z

Devices with combined IRQs would call the cortexm_isr_end handler twice
when it is part of the irq_handler routine.

mfrey/RIOT,josephnoir/RIOT,OTAkeys/RIOT,smlng/RIOT,BytesGalore/RIOT,kaspar030/RIOT,A-Paul/RIOT,yogo1212/RIOT,mfrey/RIOT,biboc/RIOT,OTAkeys/RIOT,kYc0o/RIOT,gebart/RIOT,rfuentess/RIOT,biboc/RIOT,A-Paul/RIOT,josephnoir/RIOT,mtausig/RIOT,basilfx/RIOT,BytesGalore/RIOT,smlng/RIOT,josephnoir/RIOT,biboc/RIOT,OTAkeys/RIOT,kYc0o/RIOT,jasonatran/RIOT,cladmi/RIOT,lazytech-org/RIOT,gebart/RIOT,miri64/RIOT,miri64/RIOT,OlegHahm/RIOT,cladmi/RIOT,authmillenon/RIOT,smlng/RIOT,kaspar030/RIOT,kYc0o/RIOT,rfuentess/RIOT,aeneby/RIOT,authmillenon/RIOT,josephnoir/RIOT,lazytech-org/RIOT,jasonatran/RIOT,BytesGalore/RIOT,authmillenon/RIOT,kYc0o/RIOT,A-Paul/RIOT,jasonatran/RIOT,x3ro/RIOT,cladmi/RIOT,biboc/RIOT,gebart/RIOT,basilfx/RIOT,mtausig/RIOT,lazytech-org/RIOT,jasonatran/RIOT,aeneby/RIOT,ant9000/RIOT,smlng/RIOT,x3ro/RIOT,mfrey/RIOT,basilfx/RIOT,authmillenon/RIOT,aeneby/RIOT,toonst/RIOT,mfrey/RIOT,x3ro/RIOT,toonst/RIOT,gebart/RIOT,gebart/RIOT,RIOT-OS/RIOT,lazytech-org/RIOT,yogo1212/RIOT,miri64/RIOT,jasonatran/RIOT,toonst/RIOT,rfuentess/RIOT,OlegHahm/RIOT,A-Paul/RIOT,basilfx/RIOT,cladmi/RIOT,lazytech-org/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,yogo1212/RIOT,smlng/RIOT,toonst/RIOT,RIOT-OS/RIOT,miri64/RIOT,mtausig/RIOT,mtausig/RIOT,mfrey/RIOT,aeneby/RIOT,OlegHahm/RIOT,cladmi/RIOT,OTAkeys/RIOT,OlegHahm/RIOT,BytesGalore/RIOT,OTAkeys/RIOT,A-Paul/RIOT,x3ro/RIOT,rfuentess/RIOT,miri64/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,ant9000/RIOT,x3ro/RIOT,OlegHahm/RIOT,yogo1212/RIOT,josephnoir/RIOT,aeneby/RIOT,ant9000/RIOT,kYc0o/RIOT,kaspar030/RIOT,kaspar030/RIOT,BytesGalore/RIOT,toonst/RIOT,mtausig/RIOT,authmillenon/RIOT,ant9000/RIOT,ant9000/RIOT,rfuentess/RIOT,biboc/RIOT,basilfx/RIOT,yogo1212/RIOT,kaspar030/RIOT,RIOT-OS/RIOT