package/x11r7/xdriver_xf86-video-tga: remove package

Building this package is broken with X.org xserver 21.

Fixes:
http://autobuild.buildroot.net/results/de5/de5efd922edb9eb7dc9981b5f10ea402487ee431/


Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>