power: imx8m-power-domain: Add delay to align with kernel driver

power: imx8m-power-domain: Add delay to align with kernel driver

In the imx8m power domain kernel driver, there is an extra udelay(5)
prior to requesting the domain to power up:

https://github.com/torvalds/linux/blob/v6.3/drivers/soc/imx/gpcv2.c#L347-L375

Haven't observed any issues due to the lack of this delay in U-Boot yet,
but better to align it with the kernel driver implementation.

Signed-off-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Marek Vasut <marex@denx.de>