hw/misc/npcm7xx_clk: Don't leak string in npcm7xx_clk_sel_init()

hw/misc/npcm7xx_clk: Don't leak string in npcm7xx_clk_sel_init()

In npcm7xx_clk_sel_init() we allocate a string with g_strdup_printf().
Use g_autofree so we free it rather than leaking it.

(Detected with the clang leak sanitizer.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20220308170302.2582820-1-peter.maydell@linaro.org