gpio.c: fix segfault on isrExit in python because of double Py_DECREF
gpio.c: fix segfault on isrExit in python because of double Py_DECREF

Py_DECREF is not required here as no interpreter is clever enough to handle
this reference causing a double free on isrExit(). Closes #265

Signed-off-by: Brendan Le Foll <3e0e8c4069934e8b47d99704927a85c66c0ceb33@intel.com>

Propanu/mraa,STANAPO/mraa,whbruce/mraa,nioinnovation/mraa,KurtE/mraa,stefan-andritoiu/mraa-gpio-chardev,allela-roy/mraa,g-vidal/mraa,Hbrinj/mraa,sergev/mraa,smileboywtu/mraa,sergev/mraa,g-vidal/mraa,smileboywtu/mraa,ncrastanaren/mraa,SyrianSpock/mraa,alex1818/mraa,jontrulson/mraa,jontrulson/mraa,nioinnovation/mraa,ncrastanaren/mraa,ProfFan/mraa,neuroidss/mraa,matt-auld/mraa,sergev/mraa,Propanu/mraa,yongli3/mraa,sergev/mraa,malikabhi05/mraa,Hbrinj/mraa,spitfire88/mraa,Pillar1989/mraa,intel-iot-devkit/mraa,anonymouse64/mraa,stefan-andritoiu/mraa,Pillar1989/mraa,stefan-andritoiu/mraa-gpio-chardev,jontrulson/mraa,yongli3/mraa,alext-mkrs/mraa,Hbrinj/mraa,Propanu/mraa,matt-auld/mraa,w4ilun/mraa,w4ilun/mraa,Pillar1989/mraa,Kiritoalex/mraa,anonymouse64/mraa,yongli3/mraa,allela-roy/mraa,Propanu/mraa,petreeftime/mraa,tripzero/mraa,tripzero/mraa,yoyojacky/mraa,spitfire88/mraa,petreeftime/mraa,stefan-andritoiu/mraa,spitfire88/mraa,arunlee77/mraa,SyrianSpock/mraa,stefan-andritoiu/mraa,intel-iot-devkit/mraa,smileboywtu/mraa,Kiritoalex/mraa,allela-roy/mraa,alext-mkrs/mraa,ncrastanaren/mraa,g-vidal/mraa,malikabhi05/mraa,Hbrinj/mraa,andreivasiliu2211/mraa,damcclos/mraa,andreivasiliu2211/mraa,petreeftime/mraa,jontrulson/mraa,ProfFan/mraa,sergev/mraa,ProfFan/mraa,stefan-andritoiu/mraa-gpio-chardev,stefan-andritoiu/mraa,mircea/mraa,anonymouse64/mraa,alex1818/mraa,whbruce/mraa,whbruce/mraa,stefan-andritoiu/mraa-gpio-chardev,mircea/mraa,andreivasiliu2211/mraa,arfoll/mraa,w4ilun/mraa,malikabhi05/mraa,KurtE/mraa,intel-iot-devkit/mraa,Kiritoalex/mraa,yoyojacky/mraa,ProfFan/mraa,STANAPO/mraa,ncrastanaren/mraa,alext-mkrs/mraa,damcclos/mraa,KurtE/mraa,yoyojacky/mraa,stefan-andritoiu/mraa,tripzero/mraa,arfoll/mraa,g-vidal/mraa,damcclos/mraa,KurtE/mraa,arunlee77/mraa,stefan-andritoiu/mraa-gpio-chardev,alext-mkrs/mraa,intel-iot-devkit/mraa,spitfire88/mraa,arfoll/mraa,arfoll/mraa,g-vidal/mraa,andreivasiliu2211/mraa,Jon-ICS/mraa,ncrastanaren/mraa,KurtE/mraa,SyrianSpock/mraa,yongli3/mraa,mircea/mraa,malikabhi05/mraa,STANAPO/mraa,intel-iot-devkit/mraa,malikabhi05/mraa,alext-mkrs/mraa,arunlee77/mraa,alex1818/mraa,jontrulson/mraa,Propanu/mraa,neuroidss/mraa,Jon-ICS/mraa,Jon-ICS/mraa,whbruce/mraa,nioinnovation/mraa,arunlee77/mraa,petreeftime/mraa,arfoll/mraa,neuroidss/mraa,w4ilun/mraa,yongli3/mraa,matt-auld/mraa