arm64: dts: allwinner: h313: enable DVFS for Tanix TX1

arm64: dts: allwinner: h313: enable DVFS for Tanix TX1

The merging of the Tanix TX1 .dts file overlapped with the introduction
of the CPU OPP .dtsi file, so the TX1 wasn't covered by the patch
enabling DVFS for all boards.

Add the missing include of that OPP .dtsi file, to allow the box to run
at up to 1.3GHz, and enable power saving by using lower OPPs.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Link: https://patch.msgid.link/20241215212533.12707-1-andre.przywara@arm.com
Signed-off-by: Chen-Yu Tsai <wens@csie.org>