rockchip: px30: Fixup PMUGRF registers layout order

According to the PX30 TRM, the iomux registers come first, before the pull
and strength control registers.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Reviewed-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>