devices: interrupt: add simple resample
devices: interrupt: add simple resample

Instead of coupling the reading of the event fd and the resampling of
the interrupt, add a separate member to just do the resample.

This will be used by async code that waits for and reads the event fd in
one step.

Change-Id: Ic5b1fd9adf8e32a572f31dc1c0c5ab32e94f4981
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/2268978
Commit-Queue: Dylan Reid <c791bfe44996c1eed9c7149a0c5f12a86d58eb85@chromium.org>
Tested-by: Dylan Reid <c791bfe44996c1eed9c7149a0c5f12a86d58eb85@chromium.org>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Reviewed-by: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>

google/crosvm,google/crosvm,google/crosvm,google/crosvm