dt-bindings: reserved-memory: rmtfs: Allow guard pages

dt-bindings: reserved-memory: rmtfs: Allow guard pages

On some Qualcomm platforms the firwmare, or hardware, does not
gracefully handle memory protection of the rmtfs memory region when
placed adjacent to other protected region. Some DeviceTree authors have
worked around this issue by explicitly reserving the space around the
region, but this prevents such author to use rely on the OS to place the
region, through the use of "size" (instead of a fixed location).

Introduce a flag to indicate that guard pages need be carved at the
beginning and end of the memory region. The user shall account for the
two pages in the defined size.

Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230920-rmtfs-mem-guard-pages-v3-1-305b37219b78@quicinc.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>