staging: r8188eu: rename symbols in rtw_read*() and rtw_write*()

staging: r8188eu: rename symbols in rtw_read*() and rtw_write*()

Rename variables in rtw_read{8.16.32}() and in rtw_write{8,16,32,N}()
because of unnecessary 'p' (that probably stand for "pointer to") and
'w' (that probably stands for "word"):

	pio_priv => io_priv;
	pintfhdl => intf;
	wvalue => value.

Co-developed-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Fabio M. De Francesco <fmdefrancesco@gmail.com>
Link: https://lore.kernel.org/r/20210924122705.3781-7-fmdefrancesco@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>