config: Drop CONFIG_ARCH_DMA_PIO_WORDS

This is not defined by any board in U-Boot.
Signed-off-by: NSimon Glass <sjg@chromium.org>

arch/arm/include/asm/imx-common/dma.h

@@ -16,12 +16,7 @@
 #include <linux/list.h>
 #include <linux/compiler.h>
 
-#ifndef	CONFIG_ARCH_DMA_PIO_WORDS
-#define	DMA_PIO_WORDS		15
-#else
-#define	DMA_PIO_WORDS		CONFIG_ARCH_DMA_PIO_WORDS
-#endif
-
+#define DMA_PIO_WORDS		15
 #define MXS_DMA_ALIGNMENT	ARCH_DMA_MINALIGN
 
 /*

scripts/config_whitelist.txt

@@ -109,7 +109,6 @@ CONFIG_AP_SH4A_4A
 CONFIG_ARCH_ADPAG101P
 CONFIG_ARCH_CPU_INIT
 CONFIG_ARCH_CSB226
-CONFIG_ARCH_DMA_PIO_WORDS
 CONFIG_ARCH_EARLY_INIT_R
 CONFIG_ARCH_HAS_ILOG2_U32
 CONFIG_ARCH_HAS_ILOG2_U64