ARM: 5678/1: SSP/SPI PL022 polarity terminology fix

The definition of the SPI clock phase for the Motorola mode of
the PL022 driver was incorrect: the spec had been interpreted as
data being recieved on rising or falling edge of the clocks while
the correct interpretation is that data can be recieved on the
first or second edge transition, falling or rising depending on
the polarity setting.

Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>