target/arm: Store cpregs key in the hash table directly

target/arm: Store cpregs key in the hash table directly

Cast the uint32_t key into a gpointer directly, which
allows us to avoid allocating storage for each key.

Use g_hash_table_lookup when we already have a gpointer
(e.g. for callbacks like count_cpreg), or when using
get_arm_cp_reginfo would require casting away const.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20220501055028.646596-12-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>