mips32: add fastdata loader working area

Add a working area that is preserved between calls to
mips_m4k_bulk_write_memory - this gives us a speed increase
of approx 3kb/sec during flash writes to the pic32mx.

This area is released during a resume/reset.

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

src/target/mips32.h

@@ -57,6 +57,9 @@ struct mips32_common
 	uint32_t core_regs[MIPS32NUMCOREREGS];
 	enum mips32_isa_mode isa_mode;
 
+	/* working area for fastdata access */
+	struct working_area *fast_data_area;
+
 	int bp_scanned;
 	int num_inst_bpoints;
 	int num_data_bpoints;