xtensa: remove ZONE_DMA

ZONE_DMA is intended for magic < 32-bit pools (usually ISA DMA), which
isn't required on xtensa.  Move all the non-highmem memory into
ZONE_NORMAL instead to match other architectures.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/Kconfig

@@ -1,7 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
-config ZONE_DMA
-	def_bool y
-
 config XTENSA
 	def_bool y
 	select ARCH_HAS_SG_CHAIN

arch/xtensa/mm/init.c

@@ -71,7 +71,7 @@ void __init zones_init(void)
 {
 	/* All pages are DMA-able, so we put them all in the DMA zone. */
 	unsigned long zones_size[MAX_NR_ZONES] = {
-		[ZONE_DMA] = max_low_pfn - ARCH_PFN_OFFSET,
+		[ZONE_NORMAL] = max_low_pfn - ARCH_PFN_OFFSET,
 #ifdef CONFIG_HIGHMEM
 		[ZONE_HIGHMEM] = max_pfn - max_low_pfn,
 #endif