The Allwinner A64's GPU has currently three operating points. However,
the BSP runs the GPU fixed at 432 MHz. In addition, at least one of the
devices using that SoC - the pinephone - shows unstabilities (see link)
that can be circumvented by running the GPU at a fixed rate.

Therefore, remove the other two operating points from the GPU OPP table,
so that the GPU runs at a fixed rate of 432 MHz.

Link: https://gitlab.com/postmarketOS/pmaports/-/issues/805Acked-by: Erico Nunes <nunes.erico@gmail.com>
Signed-off-by: Frank Oltmanns <frank@oltmanns.dev>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20240310-pinephone-pll-fixes-v4-5-46fc80c83637@oltmanns.devSigned-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>