ipu_common: Let the MX6 IPU clock be calculated in run-time

ipu_common: Let the MX6 IPU clock be calculated in run-time

MX6Q/QP IPU operates at 264MHz and MX6DL IPU at 198MHz.

When running a SPL target, which supports multiple MX6 variants we cannot
properly setup the IPU clock frequency via CONFIG_IPUV3_CLK option as
such decision is done in build-time currently.

Remove the CONFIG_IPUV3_CLK option and let the IPU clock frequency be
configured in run-time on mx6.

Reported-by: Eric Nelson <[email protected]>
Signed-off-by: Fabio Estevam <[email protected]>
Reviewed-by: Eric Nelson <[email protected]>
Reviewed-by: Stefano Babic <[email protected]>
[agust: fixed #endif in cgtqmx6eval.h]
Signed-off-by: Anatolij Gustschin <[email protected]>