staging: rtl8192u: check return value of rtl8192_read_eeprom_info

The call of rtl8192_read_eeprom_info may fail, therefore its return
value must be checked and propagated in the case of error

Signed-off-by: Salah Triki <salah.triki@acm.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>