block: don't select PERCPU_RWSEM

The block device doesn't use percpu rw-semaphore anymore, so don't select
it for compilation.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/Kconfig b/block/Kconfig
index 4a85ccf8..a7e40a7 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -4,7 +4,6 @@
 menuconfig BLOCK
        bool "Enable the block layer" if EXPERT
        default y
-       select PERCPU_RWSEM
        help
 	 Provide block layer support for the kernel.