staging: rtl8723au: change parameter type in rtl8723a_set_rssi_cmd declaration

Previosly the function had the following prototype:
int rtl8723a_set_rssi_cmd(struct rtw_adapter *padapter, u8 *param)

My suggestion here is to modify the prototype this way:
int rtl8723a_set_rssi_cmd(struct rtw_adapter *padapter, u32 param)

We can do this based on the following considerations:
1. rtl8723a_set_rssi_cmd is used only with 32-bit "param" values
2. There's no point in using "u8 *param" until we pass param length
3. As we just read "param", it's ok to pass it by value

Signed-off-by: Anatoly Stepanov <drivengroove@gmail.com>
Acked-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>