xtensa: switch to little endianness

Current gcc options only support the little endian mode on Xtensa,
switch over to it.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>

Author: lyakh

target-xtensa.c

@@ -22,7 +22,7 @@ static void predefine_xtensa(const struct target *self)
 const struct target target_xtensa = {
 	.mach = MACH_XTENSA,
 	.bitness = ARCH_LP32,
-	.big_endian = true,
+	.big_endian = false,
 
 	.bits_in_longdouble = 64,