spi/pl022: fix erroneous platform data in U300

This fixes an erroneous use of LSB first in the U300 machine, the
PL022 used in U300 is a standard ARM core that doesn't support this
bit so it should never have been set.

Cc: Kevin Wells <wellsk40@gmail.com>OA
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>