ARM: dts: qcom: msm8926-htc-memul: Add rmtfs memory node

Add the rmtfs-mem node which was part of one of the "unknown" memory
reservation. Split that one, make sure the reserved-memory in total
still covers the same space.

Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
Link: https://lore.kernel.org/r/20240121-memul-rmtfs-v1-1-e9da29b1f856@z3ntu.xyz


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