MIPS: update arch_info access to match other targets

- add target_to_mips32 and target_to_m4k to match test of codebase.
 - mips32_arch_state now shows if processer is running mips16e isa.

Signed-off-by: Spencer Oliver <ntfreak@users.sourceforge.net>

src/target/mips_m4k.h

@@ -35,6 +35,13 @@ struct mips_m4k_common
 	struct mips32_common mips32_common;
 };
 
+static inline struct mips_m4k_common *
+target_to_m4k(struct target *target)
+{
+	return container_of(target->arch_info,
+			struct mips_m4k_common, mips32_common);
+}
+
 int mips_m4k_bulk_write_memory(struct target *target,
 		uint32_t address, uint32_t count, uint8_t *buffer);