wil6210: fix check for sparrow D0 FW file

Driver fails to load FW for sparrow D0 devices in some cases.
Fix this by returning correct value from wil_fw_verify_file_exists
when D0 FW file is not detected for any reason.

Change-Id: I11f4e63c70f0f269372e780b3659d981924c8963
Signed-off-by: Hamad Kadmany <qca_hkadmany@qca.qualcomm.com>
Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
Git-commit: 4d4f8132f72b78d1260ec9afa94c3b44deb12adf
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git


Signed-off-by: Maya Erez <merez@codeaurora.org>