spi: dw: Remove not-going-to-be-supported code for Baikal SoC

As noticed in the discussion [1] the Baikal SoC and platforms
are not going to be finalized, hence remove stale code.

Link: https://lore.kernel.org/lkml/22b92ddf-6321-41b5-8073-f9c7064d3432@infradead.org/ [1]
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260127210541.4068379-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: andy-shev

drivers/spi/Kconfig

@@ -385,33 +385,6 @@ config SPI_DW_MMIO
 	tristate "Memory-mapped io interface driver for DW SPI core"
 	depends on HAS_IOMEM
 
-config SPI_DW_BT1
-	tristate "Baikal-T1 SPI driver for DW SPI core"
-	depends on MIPS_BAIKAL_T1 || COMPILE_TEST
-	select MULTIPLEXER
-	help
-	  Baikal-T1 SoC is equipped with three DW APB SSI-based MMIO SPI
-	  controllers. Two of them are pretty much normal: with IRQ, DMA,
-	  FIFOs of 64 words depth, 4x CSs, but the third one as being a
-	  part of the Baikal-T1 System Boot Controller has got a very
-	  limited resources: no IRQ, no DMA, only a single native
-	  chip-select and Tx/Rx FIFO with just 8 words depth available.
-	  The later one is normally connected to an external SPI-nor flash
-	  of 128Mb (in general can be of bigger size).
-
-config SPI_DW_BT1_DIRMAP
-	bool "Directly mapped Baikal-T1 Boot SPI flash support"
-	depends on SPI_DW_BT1
-	help
-	  Directly mapped SPI flash memory is an interface specific to the
-	  Baikal-T1 System Boot Controller. It is a 16MB MMIO region, which
-	  can be used to access a peripheral memory device just by
-	  reading/writing data from/to it. Note that the system APB bus
-	  will stall during each IO from/to the dirmap region until the
-	  operation is finished. So try not to use it concurrently with
-	  time-critical tasks (like the SPI memory operations implemented
-	  in this driver).
-
 endif
 
 config SPI_DLN2

drivers/spi/Makefile

@@ -54,7 +54,6 @@ obj-$(CONFIG_SPI_DLN2)			+= spi-dln2.o
 obj-$(CONFIG_SPI_DESIGNWARE)		+= spi-dw.o
 spi-dw-y				:= spi-dw-core.o
 spi-dw-$(CONFIG_SPI_DW_DMA)		+= spi-dw-dma.o
-obj-$(CONFIG_SPI_DW_BT1)		+= spi-dw-bt1.o
 obj-$(CONFIG_SPI_DW_MMIO)		+= spi-dw-mmio.o
 obj-$(CONFIG_SPI_DW_PCI)		+= spi-dw-pci.o
 obj-$(CONFIG_SPI_EP93XX)		+= spi-ep93xx.o