qtsystems: Change branch from stable to 5.3
qtsystems: Change branch from stable to 5.3

Stable branch was removed on mainline and now 5.3
is used.

Signed-off-by: Diego Sueiro <ad8405088babfd9de78621db022334230b00cda7@gmail.com>
Signed-off-by: Otavio Salvador <1d31b11c1b92bf5d043d36edfe7174db39a6b891@ossystems.com.br>

sapiippo/meta-qt5,meta-qt5/meta-qt5,timopulkkinen/meta-qt5,cjp256/meta-qt5,jruffin/meta-qt5,meta-qt5/meta-qt5,kraj/meta-qt5,opendreambox/meta-qt5,opendreambox/meta-qt5,Ivan-SB/meta-qt5,Tofee/meta-qt5,timopulkkinen/meta-qt5,sapiippo/meta-qt5,kraj/meta-qt5,opendreambox/meta-qt5,schnitzeltony/meta-qt5,timopulkkinen/meta-qt5,timopulkkinen/meta-qt5,Ivan-SB/meta-qt5,jruffin/meta-qt5,Tofee/meta-qt5,schnitzeltony/meta-qt5,cjp256/meta-qt5