acpi: Move acpi_write_tables() to a generic header

This function is used by both x86 and sandbox. Put it in a common header
file.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/include/asm/acpi_table.h b/arch/sandbox/include/asm/acpi_table.h
index ae17f6c..cb10eb5 100644
--- a/arch/sandbox/include/asm/acpi_table.h
+++ b/arch/sandbox/include/asm/acpi_table.h
@@ -6,6 +6,6 @@
 #ifndef __ASM_ACPI_TABLE_H__
 #define __ASM_ACPI_TABLE_H__
 
-ulong write_acpi_tables(ulong start);
+/* Empty for now, this file is required by acpi/acpi_table.h */
 
 #endif /* __ASM_ACPI_TABLE_H__ */
diff --git a/arch/x86/include/asm/acpi_table.h b/arch/x86/include/asm/acpi_table.h
index 39547de..226753b 100644
--- a/arch/x86/include/asm/acpi_table.h
+++ b/arch/x86/include/asm/acpi_table.h
@@ -64,8 +64,6 @@
  */
 int acpi_create_gnvs(struct acpi_global_nvs *gnvs);
 
-ulong write_acpi_tables(ulong start);
-
 /**
  * acpi_get_rsdp_addr() - get ACPI RSDP table address
  *
diff --git a/include/acpi/acpi_table.h b/include/acpi/acpi_table.h
index c98c874..4030d25 100644
--- a/include/acpi/acpi_table.h
+++ b/include/acpi/acpi_table.h
@@ -913,6 +913,16 @@
  */
 int acpi_fill_csrt(struct acpi_ctx *ctx);
 
+/**
+ * write_acpi_tables() - Write out the ACPI tables
+ *
+ * This writes all ACPI tables to the given address
+ *
+ * @start: Start address for the tables
+ * @return address of end of tables, where the next tables can be written
+ */
+ulong write_acpi_tables(ulong start);
+
 #endif /* !__ACPI__*/
 
 #include <asm/acpi_table.h>