brcmfmac: Cleanup brcmf_fw_request_done()

The "cur" variable is now only used for a debug print and we already
print the same info from brcmf_fw_complete_request(), so the debug print
does not provide any extra info and we can remove it.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>