MAINTAINERS: clk: imx: add git tree and dt-bindings files

The i.MX clocks dt-bindings are going through the same tree as
the drivers, so add them to the same entry. Also add the git
tree and branch used.

Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Link: https://lore.kernel.org/r/20220216132214.258865-1-abel.vesa@nxp.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>