arm64: dts: qcom: sagami: correct firmware paths

Correct firmware paths for the Sony Xperia Sagami devices to include the
SoC name, vendor and platform names.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220919190037.2122284-5-dmitry.baryshkov@linaro.org