xtensa: add flat support

Add the arch-specific header for flat support on xtensa in preparation
for the Xtensa S6000 nommu port.
Signed-off-by: NOskar Schirmer <os@emlix.com>
Signed-off-by: NJohannes Weiner <jw@emlix.com>
Signed-off-by: NChris Zankel <chris@zankel.net>

arch/xtensa/include/asm/flat.h

+#ifndef __ASM_XTENSA_FLAT_H
+#define __ASM_XTENSA_FLAT_H
+
+#define flat_argvp_envp_on_stack()			0
+#define flat_old_ram_flag(flags)			(flags)
+#define flat_reloc_valid(reloc, size)			((reloc) <= (size))
+#define flat_get_addr_from_rp(rp, relval, flags, p)	get_unaligned(rp)
+#define flat_put_addr_at_rp(rp, val, relval	)	put_unaligned(val, rp)
+#define flat_get_relocate_addr(rel)			(rel)
+#define flat_set_persistent(relval, p)			0
+
+#endif /* __ASM_XTENSA_FLAT_H */