ANDROID: move up spin_unlock_bh() ahead of remove_proc_entry()

It causes BUG because remove_proc_entry may sleep while holding spinlock.

BUG: scheduling while atomic: ip6tables-resto/887/0x00000202
[<c0f03f00>] (wait_for_completion) from [<c031b8c8>] (proc_entry_rundown+0x74/0xd0)
[<c031b854>] (proc_entry_rundown) from [<c03225c4>] (remove_proc_entry+0xc0/0x18c)
[<c0322504>] (remove_proc_entry) from [<c0d656e0>] (quota_mt2_destroy+0x88/0xa8)
[<c0d65658>] (quota_mt2_destroy) from [<c0e405f0>] (cleanup_entry+0x6c/0xf0)
[<c0e40584>] (cleanup_entry) from [<c0e41400>] (do_replace.constprop.2+0x314/0x438)
[<c0e410ec>] (do_replace.constprop.2) from [<c0e41640>] (do_ip6t_set_ctl+0x11c/0x238)
[<c0e41524>] (do_ip6t_set_ctl) from [<c0d2e7ec>] (nf_setsockopt+0xd4/0xf0)
[<c0d2e718>] (nf_setsockopt) from [<c0e16bb8>] (ipv6_setsockopt+0x90/0xb8)
[<c0e16b28>] (ipv6_setsockopt) from [<c0e1e908>] (rawv6_setsockopt+0x54/0x22c)
[<c0e1e8b4>] (rawv6_setsockopt) from [<c0cb48dc>] (sock_common_setsockopt+0x28/0x30)
[<c0cb48b4>] (sock_common_setsockopt) from [<c0cb3ac8>] (SyS_setsockopt+0xb8/0x110)
[<c0cb3a10>] (SyS_setsockopt) from [<c01094e0>] (ret_fast_syscall+0x0/0x48)

This is a fix for an Android specific feature which was imported
from unofficial upstream (xtables-addons), which also has the same issue:
  https://sourceforge.net/p/xtables-addons/xtables-addons/ci/master/tree/extensions/xt_quota2.c#l235

After this change the proc entry may now be removed later, when we're already
adding another one, potentially with the same name, this will simply
fail during creation, see error path for this at:
  https://sourceforge.net/p/xtables-addons/xtables-addons/ci/master/tree/extensions/xt_quota2.c#l179



Bug: 143092160
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Signed-off-by: DongJoo Kim <micomx@gmail.com>
Change-Id: I3ff3883738353785f5792c5f06bf6b72985c4c68