bcache: Fix building error on MIPS

This patch try to fix the building error on MIPS. The reason is MIPS
has already defined the PTR macro, which conflicts with the PTR macro
in include/uapi/linux/bcache.h.

[fixed by mlyle: corrected a line-length issue]

Cc: stable@vger.kernel.org
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Reviewed-by: Michael Lyle <mlyle@lyle.org>
Signed-off-by: Michael Lyle <mlyle@lyle.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/include/uapi/linux/bcache.h b/include/uapi/linux/bcache.h
index 90fc490..821f71a 100644
--- a/include/uapi/linux/bcache.h
+++ b/include/uapi/linux/bcache.h
@@ -91,7 +91,7 @@
 
 #define PTR_CHECK_DEV			((1 << PTR_DEV_BITS) - 1)
 
-#define PTR(gen, offset, dev)						\
+#define MAKE_PTR(gen, offset, dev)					\
 	((((__u64) dev) << 51) | ((__u64) offset) << 8 | gen)
 
 /* Bkey utility code */