arch: arm: generalise ARCH_QCOM platform

generalise ARCH_QCOM platform to support new 32-bit
qcom platforms.

Change-Id: I412a83a2f756b02d6b521983501de780835dc118
Signed-off-by: Srinivas Ramana <sramana@codeaurora.org>
[jshriram: Fix merge conflicts]
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>
[akdwived: Added "select GENERIC_IRQ_MIGRATION" with hotplug]
Signed-off-by: Avaneesh Kumar Dwivedi <akdwived@codeaurora.org>