ARM: dts: mdm: Support download mode through secure I/O on 9x45

Add the TCSR_BOOT_MISC_DETECT register address to the
qcom,pshold device on 8996 configuring Download Mode / EDL by means
of a Secure IO call rather than a direct SCM call.

Atomic SCM calls for this purpose are being deprecated by future
trustzone image software.

Change-Id: Ic35aabed71c24be53910829937c47fdd8ac80c46
Signed-off-by: Meghana Ashok <meghanaa@codeaurora.org>