clk: imx8mq: add GPIO clocks to clock tree

i.MX8MQ has clock gate for each GPIO bank, add them
into clock tree for GPIO driver to manage.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>