[RFC, PATCH v2] libertas: unify request_firmware failure

[Holger Schurig]

> -		lbs_pr_err("can't load helper firmware\n");
> +		lbs_pr_err("request_firmware() failed with %d\n", ret);
> +		lbs_pr_err("helper firmware libertas_cs_helper.fw not found\n"); ret = -ENODEV;

While I don't have a problem with the idea per
se, I don't like it outputting two error lines now.

So for if_cs.c, I like the original code better.

I don't care to emit the error number, won't be usable to most
people anyway. And I don't care about outputting the filename,
because udev will already show you the filename if it doesn't
find what was requested.