arm64: dts: qcom: Split elish dts into common dtsi and elish-boe dts

There are two panel variants of xiaomi-elish, BOE and CSOT panels.
In order to support both panels, so split elish dts into common dtsi
and elish-boe dts.

Signed-off-by: Jianhua Lu <lujianhua000@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230323005925.23179-1-lujianhua000@gmail.com