ANDROID: fs: epoll: use freezable blocking call

Avoid waking up every thread sleeping in an epoll_wait call during
suspend and resume by calling a freezable blocking call.  Previous
patches modified the freezer to avoid sending wakeups to threads
that are blocked in freezable blocking calls.

This call was selected to be converted to a freezable call because
it doesn't hold any locks or release any resources when interrupted
that might be needed by another freezing task or a kernel driver
during suspend, and is a common site where idle userspace tasks are
blocked.

[CPNOTE: 20/07/21] Lee: Pinged the bug for status

Bug: 77139736
Bug: 120440023
[ccross: This was upstream (https://lkml.org/lkml/2013/5/6/823), but
         reverted because it reportedly caused memory corruption on
         32-bit x86 (https://patchwork.kernel.org/patch/3162301/).

]
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[gregkh: add this back after the 5.11-rc1 merge mess]
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: Ia8268d310c00f0cfa6c01f36f3fa528e04f206e0