staging: rts5208: fix line style warnings in spi.c

 This patch fixes the following checkpatch.pl warning in spi.c:
 WARNING: line over 80 characters

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>