ARM: keystone: enable DMA zone for LPAE

Keystone II peripheral devices support 32-bit DMA and hence can access only
first 2GB of the memory address space. So set the platform dma_zone_size
to handle that case.
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

arch/arm/mach-keystone/Kconfig

@@ -12,6 +12,7 @@ config ARCH_KEYSTONE
 	select COMMON_CLK_KEYSTONE
 	select TI_EDMA
 	select ARCH_SUPPORTS_BIG_ENDIAN
+	select ZONE_DMA if ARM_LPAE
 	help
 	  Support for boards based on the Texas Instruments Keystone family of
 	  SoCs.

arch/arm/mach-keystone/keystone.c

@@ -68,6 +68,9 @@ void keystone_restart(enum reboot_mode mode, const char *cmd)
 }
 
 DT_MACHINE_START(KEYSTONE, "Keystone")
+#if defined(CONFIG_ZONE_DMA) && defined(CONFIG_ARM_LPAE)
+	.dma_zone_size	= SZ_2G,
+#endif
 	.smp		= smp_ops(keystone_smp_ops),
 	.init_machine	= keystone_init,
 	.dt_compat	= keystone_match,