SHM Bridge is a safety mechanism allowing to limit the amount of memory
shared between the kernel and the TrustZone to regions explicitly marked
as such.

Add low-level primitives for enabling SHM bridge support as well as
creating and destroying SHM bridges to qcom-scm.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Acked-by: Andrew Halaney <ahalaney@redhat.com>
Tested-by: Andrew Halaney <ahalaney@redhat.com> # sc8280xp-lenovo-thinkpad-x13s
Tested-by: Deepti Jaggi <quic_djaggi@quicinc.com> #sa8775p-ride
Reviewed-by: Elliot Berman <quic_eberman@quicinc.com>
Link: https://lore.kernel.org/r/20240527-shm-bridge-v10-10-ce7afaa58d3a@linaro.orgSigned-off-by: Bjorn Andersson <andersson@kernel.org>