arm64: dts: qcom: x1e80100: Fix PCIe 6a reg offsets and add MHI

The actual size of the DBI region is 0xf20 and the start of the
ELBI region is 0xf40, according to the documentation. So fix them.
While at it, add the MHI region as well.

Fixes: 5eb83fc1 ("arm64: dts: qcom: x1e80100: Add PCIe nodes")
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Abel Vesa <abel.vesa@linaro.org>
Acked-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20240604-x1e80100-dts-fixes-pcie6a-v2-1-0b4d8c6256e5@linaro.org


Signed-off-by: Bjorn Andersson <andersson@kernel.org>