ARM: dts: imx7ulp: add HSRUN mode clocks

i.MX7ULP can switch CPU between RUN mode and HSRUN mode
by programming SMC1 register, different clock sources
will be used for CPU in different modes, so SMC1 can be
abstracted as a clock controller for CPU clock switch,
this patch adds support for it.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>