arm64: dts: qcom: sdm845-xiaomi-polaris: Fix sde_dsi_active pinctrl

"make dtbs_check" says:

    bias-disable: boolean property with value b'\x00\x00\x00\x00'

Fix this by dropping the offending value.

Fixes: be497abe ("arm64: dts: qcom: Add support for Xiaomi Mi Mix2s")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Caleb Connolly <caleb@connolly.tech>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/629afd26008c2b1ba5822799ea7ea5b5271895e8.1660903997.git.geert+renesas@glider.be