msm: smd: Add interrupt debugging support

Add counters for tracking interrupts.  This helps for
debugging interrupt issues and provides a centralized
place to verify that SMD interrupts are working
correctly.

This can be used as an additional verification
tool when moving interrupt configuration into
platform data and device tree.

Change-Id: Ie3936abc59f0d9a470e96a2f5da4b0390d7f7de1
Signed-off-by: Eric Holmberg <eholmber@codeaurora.org>