staging: r8188eu: always initialise efuse buffer with 0xff

staging: r8188eu: always initialise efuse buffer with 0xff

If BOOT_FROM_EEPROM is set, efuse_buf is not initialised before it is
passed to functions that read from it.

The buffer will be filled with 0x00 in this case like all local variables.
However, the parsing functions expect the buffer to be filled with 0xFF if
reading eeprom/efuse data failed. Fill the buffer with 0xFF before we try
to read the data.

Please note that this problem existed before we started using a local
buffer. Adapter->eeprompriv->efuse_eeprom_data was allocated as a part of
struct adapter by a vzalloc call in rtw_usb_if1_init.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220709171000.180481-7-martin@kaiser.cx
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>