pstore: Remove needless lock during console writes

commit b77fa617a2ff4d6beccad3d3d4b3a1f2d10368aa upstream.

Since the console writer does not use the preallocated crash dump buffer
any more, there is no reason to perform locking around it.

Fixes: 70ad35db ("pstore: Convert console write to use ->write_buf")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>