qt4: Rename bbappend to match oe-core

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Applied-by: Samuel Stirtzel <s.stirtzel@googlemail.com>
qt4-append: Removed platform dependent config modifiers

The modifiers enabled EGL support for Qt which should be a decision of the machine layer.
This could only be realized in a clean style by making qt machine dependent and adding this config options in bsp layers.

Signed-off-by: Samuel Stirtzel <s.stirtzel@googlemail.com>