remoteproc: qcom_q6v5_mss: support loading MBN file on msm8974

On MSM8974 / APQ8074, MSM8226 and MSM8926 the MSS requires loading raw
MBA image instead of the ELF file. Skip the ELF headers if mba.mbn was
specified as the firmware image.

Fixes: a5a4e02d ("remoteproc: qcom: Add support for parsing fw dt bindings")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Tested-by: Luca Weiss <luca@lucaweiss.eu> # msm8974pro-fairphone-fp2
Link: https://lore.kernel.org/r/20250706-msm8974-fix-mss-v4-1-630907dbd898@oss.qualcomm.com


[bjorn: Unwrapped the long memcpy line, to taste]
Signed-off-by: Bjorn Andersson <andersson@kernel.org>