irqchip: qcom: pdc: Add a kernel config for pdc save/restore feature

Add a kernel config for pdc save/restore feature to selectively enable
the feature only on some platforms.

Change-Id: I554574f7f063a28a9b42c476b8a51a94693ccd53
Signed-off-by: Ramachandran Venkataramani <ramavenk@codeaurora.org>