spi: dw: Initialize paddr in DW SPI MMIO private data

This field is used only for the DW SPI DMA code initialization, that's
why there were no problems with it being uninitialized in Dw SPI MMIO
driver. Since in a further patch we are going to introduce the DW SPI DMA
support in the MMIO version of the driver, lets set the field with the
physical address of the DW SPI controller registers region.

Co-developed-by: Georgy Vlasov <Georgy.Vlasov@baikalelectronics.ru>
Co-developed-by: Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru>
Signed-off-by: Georgy Vlasov <Georgy.Vlasov@baikalelectronics.ru>
Signed-off-by: Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200515104758.6934-12-Sergey.Semin@baikalelectronics.ru


Signed-off-by: Mark Brown <broonie@kernel.org>