FROMGIT: firmware_class: make firmware caching configurable

Because firmware caching generates uevent messages that are sent over
a netlink socket, it can prevent suspend on many platforms.  It's
also not always useful, so make it a configurable option.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Cc: Tim Murray <timmurray@google.com>
Cc: Venkata Narendra Kumar Gutta <vnkgutta@codeaurora.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: kernel-team@android.com
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20191113225429.118495-1-salyzyn@android.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

(cherry picked from commit c74f8056621738f5be9f5d3d7e0caa927b21aef6 git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git

 driver-core-testing)
Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 32180327
Bug: 137566496
Change-Id: I1250512b27edb56caa78d536e5ccf1fb669476ad