ubi: fastmap: Fix duplicate slab cache names while attaching

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

ubi: fastmap: Fix duplicate slab cache names while attaching

Since commit 4c39529663b9 ("slab: Warn on duplicate cache names when

DEBUG_VM=y"), the duplicate slab cache names can be detected and a

kernel WARNING is thrown out.

In UBI fast attaching process, alloc_ai() could be invoked twice

with the same slab cache name 'ubi_aeb_slab_cache', which will trigger

following warning messages:

kmem_cache of name 'ubi_aeb_slab_cache' already exists

WARNING: CPU: 0 PID: 7519 at mm/slab_common.c:107

__kmem_cache_create_args+0x100/0x5f0

Modules linked in: ubi(+) nandsim [last unloaded: nandsim]

CPU: 0 UID: 0 PID: 7519 Comm: modprobe Tainted: G 6.12.0-rc2

RIP: 0010:__kmem_cache_create_args+0x100/0x5f0

Call Trace:

__kmem_cache_create_args+0x100/0x5f0

alloc_ai+0x295/0x3f0 [ubi]

ubi_attach+0x3c3/0xcc0 [ubi]

ubi_attach_mtd_dev+0x17cf/0x3fa0 [ubi]

ubi_init+0x3fb/0x800 [ubi]

do_init_module+0x265/0x7d0

__x64_sys_finit_module+0x7a/0xc0

The problem could be easily reproduced by loading UBI device by fastmap

with CONFIG_DEBUG_VM=y.

Fix it by using different slab names for alloc_ai() callers.