[MIPS] TX39: Remove redundant tx39_blast_icache() calls

Apply commit 0550d9d1

 to c-tx39.c too.
And fix a warning in local_tx39_flush_data_cache_page().

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>