nfc: fix memory leak in llcp_sock_bind()

      sysbot reported a memory leak after a bind() has failed.

While we are at it, abort the operation if kmemdup() has failed.

BUG: memory leak
unreferenced object 0xffff888105d83ec0 (size 32):
  comm "syz-executor067", pid 7207, jiffies 4294956228 (age 19.430s)
  hex dump (first 32 bytes):
    00 69 6c 65 20 72 65 61 64 00 6e 65 74 3a 5b 34  .ile read.net:[4
    30 32 36 35 33 33 30 39 37 5d 00 00 00 00 00 00  026533097]......
  backtrace:
    [<0000000036bac473>] kmemleak_alloc_recursive /./include/linux/kmemleak.h:43 [inline]
    [<0000000036bac473>] slab_post_alloc_hook /mm/slab.h:522 [inline]
    [<0000000036bac473>] slab_alloc /mm/slab.c:3319 [inline]
    [<0000000036bac473>] __do_kmalloc /mm/slab.c:3653 [inline]
    [<0000000036bac473>] __kmalloc_track_caller+0x169/0x2d0 /mm/slab.c:3670
    [<000000000cd39d07>] kmemdup+0x27/0x60 /mm/util.c:120
    [<000000008e57e5fc>] kmemdup /./include/linux/string.h:432 [inline]
    [<000000008e57e5fc>] ll