target/i386: Fix exception classes for MOVNTPS/MOVNTPD.

Before this change, MOVNTPS and MOVNTPD were labeled as Exception Class
4 (only requiring alignment for legacy SSE instructions). This changes
them to Exception Class 1 (always requiring memory alignment), as
documented in the Intel manual.
Message-Id: <20230501111428.95998-3-ricky@rzhou.org>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>