mmc: atmel-mci: fix bad logic of sg_copy_{from,to}_buffer conversion

The conversion to sg_copy_{from,to}_buffer has been done in the wrong
way. sg_copy_to_buffer is a copy from an SG list to a linear buffer so
it can't replace memcpy(buf + offset, &value, remaining) where buf is
the virtual address of the SG. Same for sg_copy_to_buffer but in the
opposite way.

Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Suggested-by: Douglas Gilbert <dgilbert@interlog.com>
Fixes: 5b427781 ("mmc: atmel-mci: use sg_copy_{from,to}_buffer")
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>