x86/mce: Rename rcu_dereference_check_mce() to mce_log_get_idx_check()

The "rcu_" prefix misleads for it being a proper RCU interface
which is not. It basically checks whether we're preemptible or
holding the chrdev_read mutex.

Rename it accordingly.

Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/1439396985-12812-12-git-send-email-bp@alien8.de


Signed-off-by: Ingo Molnar <mingo@kernel.org>