board: beacon: imx8mp: Fix GIC clock for Overdrive mode

board: beacon: imx8mp: Fix GIC clock for Overdrive mode

There is a config option to run the PMIC at nominal voltages
which is not enabled on the i.MX8MP Beacon kit, so it the PMIC
runs at overdrive voltages.   Unfortuately, the check for this
condition to set the GIC clock parent and rate is backwards from
what it should be, and accidentally sets the GIC clock to nominal
if the PMIC is in overdrive, and sets the GIC clock to overdrive
if the PMIC is in nominal.  Fix this by inverting the logic on the
check.

Fixes: ab53bd43dbde ("arm64: imx: Add support for imx8mp-beacon-kit")
Signed-off-by: Adam Ford <aford173@gmail.com>