target-sh4: fix TLB invalidation code

In cpu_sh4_invalidate_tlb, the UTLB was invalidated twice and the
ITLB left unchaged, probably because of some unfortunate copy/paste.

Signed-off-by: Alexandre Courbot <gnurou@gmail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
