PM / devfreq: Fix buffer overflow in trans_stat_show
JIRA: https://issues.redhat.com/browse/RHEL-29457
CVE: CVE-2023-52614
Convert simple snprintf to the more secure scnprintf with size of PAGE_SIZE.
Add condition checking if we are exceeding PAGE_SIZE and exit early from loop.
Also add at the end a warning that we exceeded PAGE_SIZE and that stats is disabled.
Return -EFBIG in the case where we don't have enough space to write the full transition table.
Signed-off-by: Mark Salter msalter@redhat.com