regmap: maple: free entry on mas_store_gfp() failure

In the Linux kernel, the following vulnerability has been resolved:

regmap: maple: free entry on mas_store_gfp() failure

regcache_maple_write() allocates a new block ('entry') to merge adjacent ranges and then stores it with mas_store_gfp(). When mas_store_gfp() fails, the new 'entry' remains allocated and is never freed, leaking memory.

Free 'entry' on the failure path; on success continue freeing the replaced neighbor blocks ('lower', 'upper').