crypto: mxs-dcp - Remove global mutex

Remove mutex_lock from probe in order to avoid the following warning:

[    8.526613] Freeing unused kernel memory: 232K (c0683000 - c06bd000)
starting pid 56, tty '': '/etc/rc.d/rcS'
[    9.110314]
[    9.111864] =====================================
[    9.116603] [ BUG: init/1 still has locks held! ]
[    9.121488] 3.15.0-rc4-next-20140509-00001-g319564e #1154 Not tainted
[    9.128071] -------------------------------------
[    9.132825] 1 lock held by init/1:
[    9.136252]  #0:  (global_mutex){+.+.+.}, at: [<c0387d68>] mxs_dcp_probe+0x14
[    9.144196]
[    9.144196] stack backtrace:
[    9.148888] CPU: 0 PID: 1 Comm: init Not tainted 3.15.0-rc4-next-20140509-004
[    9.157610] [<c000da40>] (unwind_backtrace) from [<c000bda4>] (show_stack+0x)
[    9.165595] [<c000bda4>] (show_stack) from [<c00153d4>] (do_fork+0x2c8/0x3cc)
[    9.172921] [<c00153d4>] (do_fork) from [<c0015550>] (sys_vfork+0x20/0x2c)
[    9.179973] [<c0015550>] (sys_vfork) from [<c0009580>] (ret_fast_syscall+0x0)

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>