HID: bigben_worker() remove unneeded check on report_field

bigben_worker() checks report_field to be non-NULL.
The check has been added in commit
918aa1ef ("HID: bigbenff: prevent null pointer dereference")
to prevent a NULL pointer crash.
However, the true root cause was a missing check for output
reports, patched in commit
c7bf714f ("HID: check empty report_list in bigben_probe()"),
where the type-confused report list_entry was overlapping with
a NULL pointer, which was then causing the crash.

Fixes: 918aa1ef ("HID: bigbenff: prevent null pointer dereference")
Signed-off-by: Pietro Borrello <borrello@diag.uniroma1.it>
Link: https://lore.kernel.org/r/20230125-hid-unregister-leds-v4-2-7860c5763c38@diag.uniroma1.it


Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>