qt5base: fix rpi/egl support (vc_dispmanx_element_change_attributes proto mismatch)

Patch from upstream already included in the next 5.2 release

Fixes:
	http://autobuild.buildroot.net/results/347/347577bf1dee0fec3302a45f278eb253118a5b6f/build-end.log



Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>