vc4: automake: remove vc4_drm.h from the sources lists
vc4: automake: remove vc4_drm.h from the sources lists

The file was removed with earlier commit breaking 'make dist'.
Drop it from Makefile.sources since it's no longer around.

Fixes: 16985eb308e ("vc4: Switch to using the libdrm-provided
vc4_drm.h.")
Signed-off-by: Emil Velikov <f20878473f414da183da19ee25c8722cc1d711e4@collabora.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler