clk: imx: imx7d: Remove ARM_M0 clock

IMX7d does not have an M0 Core and this particular
clock doesn't seem connected to anything else.
Remove this entry from the CCM driver.

Signed-off-by: Adriana Reus <adriana.reus@nxp.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>