sony-laptop: return a negative error code in sonypi_compat_init()

Return -1 in the error handling case instead of 0, as done elsewhere in
this function.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Mattia Dongili <malattia@linux.it>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>