nvdimm/btt: Free arenas on btt_init() error paths

nvdimm/btt: Free arenas on btt_init() error paths

The arenas allocated by discover_arenas() or create_arenas() are not
freed on some error paths in btt_init(). This leaks memory when BTT
initialization fails.

Call free_arenas() from the affected error paths to release the
allocations.

[ as: commit message and log edits ]

Fixes: 5212e11fde4d ("nd_btt: atomic sector updates")
Cc: stable@vger.kernel.org
Signed-off-by: Abdun Nihaal <nihaal@cse.iitm.ac.in>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Link: https://patch.msgid.link/20260519-nvdimmleaks-v1-2-592300fb7a43@cse.iitm.ac.in
Signed-off-by: Alison Schofield <alison.schofield@intel.com>