cpu: move debug_check_watchpoint to tcg_ops

cpu: move debug_check_watchpoint to tcg_ops

commit 568496c0c0f1 ("cpu: Add callback to check architectural") and
commit 3826121d9298 ("target-arm: Implement checking of fired")
introduced an ARM-specific hack for cpu_check_watchpoint.

Make debug_check_watchpoint optional, and move it to tcg_ops.

Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210204163931.7358-15-cfontana@suse.de>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>