firmware_loader: Remove unnecessary conversion to bool

Fix the following coccicheck warnings:

./tools/testing/selftests/firmware/fw_namespace.c:98:54-59: WARNING:
conversion to bool not needed here.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Link: https://lore.kernel.org/r/1613639529-41139-1-git-send-email-jiapeng.chong@linux.alibaba.com


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