driver: viewport scale and offset xy as fixp

Prepare for v4 state delta (context switching) support.
The kernel expects these fields to be fixp, so we do too.
fbdemos: heed EGL_FBDEV_BUFFERS just like our mesa driver
utils: add "max" mode to viv_gpu_top

Find maximum throughput of various counters, this will help determining
the utilization computation. Also implement full argument parsing using
getopt.
driver: don't add pointsize output if shader doesn't set point size

Don't add pointsize output to vertex shader if that shader doesn't
assign the point size. Even if point_size_per_vertex is enabled in
rasterizer configuration. This is done because Mesa *always* sets
point_size_per_vertex to enabled with OpenGL ES, no matter what
the shader does or whether points or other primitives are rendered.
utils: add total instructions counter to viv_gpu_top

Also solve miscounting bug for a few counters.