arm64: dts: qcom: sm8150-mtp: drop incorrect amd,imageon

arm64: dts: qcom: sm8150-mtp: drop incorrect amd,imageon

The SM8150 MTP board does not have magically different GPU than the
SM8150, so it cannot use amd,imageon compatible, also pointed by
dtbs_check:

  sm8150-mtp.dtb: gpu@2c00000: compatible: 'oneOf' conditional failed, one must be fixed:
    ['qcom,adreno-640.1', 'qcom,adreno', 'amd,imageon'] is too long
    'qcom,adreno-640.1' does not match '^qcom,adreno-[0-9a-f]{8}$'
    'qcom,adreno-640.1' does not match '^amd,imageon-200\\.[0-1]$'
    'amd,imageon' was expected

The incorrect amd,imageon compatible was added in commit f30ac26def18
("arm64: dts: qcom: add sm8150 GPU nodes") to the SM8150 and later moved
to the SM8150 MTP board in commit 1642ab96efa4 ("arm64: dts: qcom:
sm8150: Don't start Adreno in headless mode") with an intention to allow
headless mode.  This should be solved via proper driver quirks, not fake
compatibles.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240821140116.436441-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>