arch: omap: add userspace export of the current GPU clock. Works mostly like scaling_cur_freq.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
arch: omap: export current IVA clock to userspace, make GPU+IVA exports match
similar to scaling_cur_freq, gpu_cur_freq and iva_cur_freq