net: ipa: Grab IMEM slice base/size from DTS

net: ipa: Grab IMEM slice base/size from DTS

This is a detail that differ per chip, and not per IPA version (and
there are cases of the same IPA versions being implemented across very
very very different SoCs).

This region isn't actually used by the driver, but we most definitely
want to iommu-map it, so that IPA can poke at the data within.

Reviewed-by: Alex Elder <elder@riscstar.com>
Acked-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://patch.msgid.link/20260302-topic-ipa_imem-v6-3-c0ebbf3eae9f@oss.qualcomm.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>