soc: qcom: Add missing MSM_DEBUG_LAR_UNLOCK Kconfig

Support for this feature is present in the memory_dump_v2 driver,
but the Kconfig is missing.  Add it.

Change-Id: I72e64756a86378be3adcc00119c8db3b9d465e68
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>
[abhimany: resolve trivial merge conflicts]
Signed-off-by: Abhimanyu Kapur <abhimany@codeaurora.org>