mtd: spinand: fix memory leak of ECC engine conf

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

mtd: spinand: fix memory leak of ECC engine conf

Memory allocated for the ECC engine conf is not released during spinand cleanup. Below kmemleak trace is seen for this memory leak:

unreferenced object 0xffffff80064f00e0 (size 8): comm "swapper/0", pid 1, jiffies 4294937458 hex dump (first 8 bytes): 00 00 00 00 00 00 00 00 ........ backtrace (crc 0): kmemleak_alloc+0x30/0x40 __kmalloc_cache_noprof+0x208/0x3c0 spinand_ondie_ecc_init_ctx+0x114/0x200 nand_ecc_init_ctx+0x70/0xa8 nanddev_ecc_engine_init+0xec/0x27c spinand_probe+0xa2c/0x1620 spi_mem_probe+0x130/0x21c spi_probe+0xf0/0x170 really_probe+0x17c/0x6e8 __driver_probe_device+0x17c/0x21c driver_probe_device+0x58/0x180 __device_attach_driver+0x15c/0x1f8 bus_for_each_drv+0xec/0x150 __device_attach+0x188/0x24c device_initial_probe+0x10/0x20 bus_probe_device+0x11c/0x160

Fix the leak by calling nanddev_ecc_engine_cleanup() inside spinand_cleanup().