staging: rtl8188eu: rename parameters of HalSetBrateCfg() - style

Rename parameters of HalSetBrateCfg() in header to avoid CamelCase
and match the names used in the function definition in hal_com.c.
mBratesOS -> brates
BrateCfg -> rate_cfg

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>