doc: driver-model: Update SPI migration status

DM_SPI migration status fror v2020.07

removed:
 lpc32xx_ssp.c
 sh_spi.c

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/doc/driver-model/migration.rst b/doc/driver-model/migration.rst
index d1fc0e6..de8c1f9 100644
--- a/doc/driver-model/migration.rst
+++ b/doc/driver-model/migration.rst
@@ -69,8 +69,6 @@
 No dm conversion yet::
 
 	drivers/spi/fsl_espi.c
-	drivers/spi/lpc32xx_ssp.c
-	drivers/spi/sh_spi.c
 	drivers/spi/soft_spi_legacy.c
 
 * Status: In progress