IB/qib: fix false-postive maybe-uninitialized warning

aarch64-linux-gcc-7 complains about code it doesn't fully understand:

drivers/infiniband/hw/qib/qib_iba7322.c: In function 'qib_7322_txchk_change':
include/asm-generic/bitops/non-atomic.h:105:35: error: 'shadow' may be used uninitialized in this function [-Werror=maybe-uninitialized]

The code is right, and despite trying hard, I could not come up with a version
that I liked better than just adding a fake initialization here to shut up the

Fixes: f931551bafe1 ("IB/qib: Add new qib driver for QLogic PCIe InfiniBand adapters")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
diff --git a/drivers/infiniband/hw/qib/qib_iba7322.c b/drivers/infiniband/hw/qib/qib_iba7322.c
index 12c4208..af9f596 100644
--- a/drivers/infiniband/hw/qib/qib_iba7322.c
+++ b/drivers/infiniband/hw/qib/qib_iba7322.c
@@ -7068,7 +7068,7 @@
 	unsigned long flags;
 	while (wait) {
-		unsigned long shadow;
+		unsigned long shadow = 0;
 		int cstart, previ = -1;