spi: spi-pxa2xx: SPI support for Intel Quark X1000

spi: spi-pxa2xx: SPI support for Intel Quark X1000

There are two SPI controllers exported by PCI subsystem for Intel Quark X1000.
The SPI memory mapped I/O registers supported by Quark are different from
the current implementation, and Quark only supports the registers of 'SSCR0',
'SSCR1', 'SSSR', 'SSDR', and 'DDS_RATE'. This patch is to enable the SPI for
Intel Quark X1000.

This piece of work is derived from Dan O'Donovan's initial work for Intel Quark
X1000 SPI enabling.

Reviewed-by: Andy Shevchenko <[email protected]>
Acked-by: Mika Westerberg <[email protected]>
Signed-off-by: Weike Chen <[email protected]>
Signed-off-by: Mark Brown <[email protected]>