nfs4: Fix kmemleak when allocate slot failed

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

nfs4: Fix kmemleak when allocate slot failed

If one of the slot allocate failed, should cleanup all the other

allocated slots, otherwise, the allocated slots will leak:

unreferenced object 0xffff8881115aa100 (size 64):

comm ""mount.nfs"", pid 679, jiffies 4294744957 (age 115.037s)

hex dump (first 32 bytes):

00 cc 19 73 81 88 ff ff 00 a0 5a 11 81 88 ff ff ...s......Z.....

00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

backtrace:

[<000000007a4c434a>] nfs4_find_or_create_slot+0x8e/0x130

[<000000005472a39c>] nfs4_realloc_slot_table+0x23f/0x270

[<00000000cd8ca0eb>] nfs40_init_client+0x4a/0x90

[<00000000128486db>] nfs4_init_client+0xce/0x270

[<000000008d2cacad>] nfs4_set_client+0x1a2/0x2b0

[<000000000e593b52>] nfs4_create_server+0x300/0x5f0

[<00000000e4425dd2>] nfs4_try_get_tree+0x65/0x110

[<00000000d3a6176f>] vfs_get_tree+0x41/0xf0

[<0000000016b5ad4c>] path_mount+0x9b3/0xdd0

[<00000000494cae71>] __x64_sys_mount+0x190/0x1d0

[<000000005d56bdec>] do_syscall_64+0x35/0x80

[<00000000687c9ae4>] entry_SYSCALL_64_after_hwframe+0x46/0xb0