arm64: Kconfig: Remove certain dependency for HOTPLUG_SIZE_BITS

With the QCOM_MEM_OFFLINE config disabled, the memblock size
gets calculated to be 0. This would break the memory hotplug
framework. Remove the dependency.

Change-Id: I6bc69727db7dbd9c47e17a654e0bc4ea3ead1425
Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>