dt-bindings: sram: qcom,imem: document sm8450

Add compatible for sm8450 IMEM.

Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/1676986616-21378-1-git-send-email-quic_mojha@quicinc.com


Signed-off-by: Rob Herring <robh@kernel.org>