test_firmware: add batched firmware tests

test_firmware: add batched firmware tests

The firmware API has a feature to enable batching requests for the same fil
e under one worker, so only one lookup is done. This only triggers if we so
happen to schedule two lookups for same file around the same time, or if
release_firmware() has not been called for a successful firmware call. This
can happen for instance if you happen to have multiple devices and one
device driver for certain drivers where the stars line up scheduling
wise.

This adds a new sync and async test trigger. Instead of adding a new
trigger for each new test type we make the tests a bit configurable so that
we could configure the tests in userspace and just kick a test through a
few basic triggers. With this, for instance the two types of sync requests:

  o request_firmware() and
  o request_firmware_direct()

can be modified with a knob. Likewise the two type of async requests:

   o request_firmware_nowait(uevent=true) and
   o request_firmware_nowait(uevent=false)

can be configured with another knob. The call request_firmware_into_buf()
has no users... yet.

The old tests are left in place as-is given they serve a few other purposes
which we are currently not interested in also testing yet. This will change
later as we will be able to just consolidate all tests under a few basic
triggers with just one general configuration setup.

We perform two types of tests, one for where the file is present and one
for where the file is not present. All test tests go tested and they now
pass for the following 3 kernel builds possible for the firmware API:

0. Most distro setup:
   CONFIG_FW_LOADER_USER_HELPER_FALLBACK=n
   CONFIG_FW_LOADER_USER_HELPER=y
1. Android:
   CONFIG_FW_LOADER_USER_HELPER_FALLBACK=y
   CONFIG_FW_LOADER_USER_HELPER=y
2. Rare build:
   CONFIG_FW_LOADER_USER_HELPER_FALLBACK=n
   CONFIG_FW_LOADER_USER_HELPER=n

Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>