Revert "irqdomain: Implement and expose API to clear IRQ mapping for radix tree"

IPCC module is never unloaded on GKI based build, so clearing of the IRQ
mappings are not needed. Remove it's implementation and usage.

This reverts commit 2fd144aa.

Change-Id: Iff747c574cced63425da3ab5adefd229d43d3ed6
Signed-off-by: Jeevan Shriram <jshriram@codeaurora.org>