CAAM: fix uninitialized spinlock issue:

[    2.965195] BUG: spinlock bad magic on CPU#1, swapper/0/1
[    2.965206]  lock: 0xac4a4e80, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
[    2.965215] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 3.10.17-rt12-02558-g6a5c2ca #13
[    2.965220] Backtrace:
[    2.965248] [<80011fbc>] (dump_backtrace+0x0/0x10c) from [<8001215c>] (show_stack+0x18/0x1c)
[    2.965260]  r6:ac05e000 r5:ac4a4e80 r4:00000000 r3:00000000
[    2.965281] [<80012144>] (show_stack+0x0/0x1c) from [<805beb18>] (dump_stack+0x20/0x28)
[    2.965293] [<805beaf8>] (dump_stack+0x0/0x28) from [<805beba0>] (spin_dump+0x80/0x94)
[    2.965304] [<805beb20>] (spin_dump+0x0/0x94) from [<805bebe0>] (spin_bug+0x2c/0x30)
[    2.965310]  r5:80707364 r4:ac4a4e80
[    2.965325] [<805bebb4>] (spin_bug+0x0/0x30) from [<8028aef0>] (do_raw_spin_lock+0x174/0x1a0)
[    2.965331]  r5:ac05fdc0 r4:ac4a4e80
[    2.965345] [<8028ad7c>] (do_raw_spin_lock+0x0/0x1a0) from [<805c2100>] (_raw_spin_lock+0x20/0x24)
[    2.965355] [<805c20e0>] (_raw_spin_lock+0x0/0x24) from [<805c185c>] (rt_spin_lock_slowlock+0x48/0x24c)
[    2.965362]  r4:ac4a4e80 r3:00000001
[    2.965371] [<805c1814>] (rt_spin_lock_slowlock+0x0/0x24c) from [<805c1d24>] (rt_spin_lock+0x2c/0x30)
[    2.965383] [<805c1cf8>] (rt_spin_lock+0x0/0x30) from [<80484f20>] (sm_keystore_slot_alloc+0x34/0x8c)
[    2.965389]  r4:ac4a4e80 r3:00000000
[    2.965399] [<80484eec>] (sm_keystore_slot_alloc+0x0/0x8c) from [<804854cc>] (caam_sm_example_init+0x1e8/0x1c48)
[    2.965411] [<804852e4>] (caam_sm_example_init+0x0/0x1c48) from [<807ba0b0>] (caam_sm_test_init+0x4c/0x64)
[    2.965420] [<807ba064>] (caam_sm_test_init+0x0/0x64) from [<8000862c>] (do_one_initcall+0x3c/0x160)
[    2.965440] [<800085f0>] (do_one_initcall+0x0/0x160) from [<80795c1c>] (kernel_init_freeable+0x104/0x1d0)
[    2.965451] [<80795b18>] (kernel_init_freeable+0x0/0x1d0) from [<805b59e8>] (kernel_init+0x10/0xec)
[    2.965462] [<805b59d8>] (kernel_init+0x0/0xec) from [<8000e518>] (ret_from_fork+0x14/0x3c)
[    2.965468]  r4:00000000 r3:00000000