staging/rtl8192u/ieee80211: use __func__ macro

Replace function names with __func__ macro.
Remove unnecessary characters in error messages.
Reported by checkpatch.pl.

Signed-off-by: Elena Afanasova <eafanasova@gmail.com>
Link: https://lore.kernel.org/r/20201020150823.35734-1-eafanasova@gmail.com


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