According to S905X2 Datasheet - Revision 07:

DMC_MON area spans 0xff638080-0xff6380c0
DDR_PLL area spans 0xff638c00-0xff638c34

Round DDR_PLL area size up to 0x40

Fixes: 90cf8e21 ("arm64: dts: meson: Add DDR PMU node")
Signed-off-by: Marc Gonzalez <mgonzalez@freebox.fr>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20230327120932.2158389-3-mgonzalez@freebox.frSigned-off-by: Neil Armstrong <neil.armstrong@linaro.org>