staging: rtl8188eu: hal: hal_intf.c: Cleaning up functions that are not used anywhere

Removes some functions that are not used anywhere.
rtw_hal_interrupt_handler() rtw_hal_sreset_get_wifi_status()

This was partially found by using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>