soc: qcom: mdt_loader: Fix error return values in mdt_header_valid()

This function is supposed to return true for valid headers and false for
invalid.  In a couple places it returns -EINVAL instead which means the
invalid headers are counted as true.  Change it to return false.

Fixes: 9f9967fe ("soc: qcom: mdt_loader: Ensure we don't read past the ELF header")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Link: https://lore.kernel.org/r/db57c01c-bdcc-4a0f-95db-b0f2784ea91f@sabinyo.mountain


Signed-off-by: Bjorn Andersson <andersson@kernel.org>