MLK-21399 irqchip: gic-v3: Rework the ERR11171 workaround

Instead of just raising irq0 for all the cores, we mask the irq0 for all the
non-target cores, this way waking up only the core we want. All of this
is done now in TF-A.

Also, since this new workaround doesn't need the IOMUX_GPR1 register here
in kernel, the IOMUX_GPR reg entry inside the gic dts node can be removed.

In order for this to work, the following commit is needed in TF-A:
 0e91ff59720d0756 ("MLK-21399 plat: imx8mq: gpc: Workaround for ERR11171")

Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Reviewed-by: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: Angus Ainslie <angus@akkea.ca>