grub2: Fix passing null to printf formats

Backport a patch that helps with this error which is found
by gcc9

(From OE-Core rev: 93419fb569b827056a422614d3dc29cd41b2b6bb)

(From OE-Core rev: 47731b43e6d287b3b03347ae94b99dea515d9a56)

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-bsp/grub/files/0001-grub-setup-Debug-message-cleanup.patch

@@ -0,0 +1,34 @@
+From 4e9d9358e0cda6d01020005eb6343e3b69f7201a Mon Sep 17 00:00:00 2001
+From: Cao jin <caoj.fnst@cn.fujitsu.com>
+Date: Tue, 3 Jul 2018 18:51:13 +0800
+Subject: [PATCH] grub-setup: Debug message cleanup
+
+Variable "root" is initialized after root device probing and is null in
+current place, so, drop it.
+
+Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
+Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
+---
+Upstream-Status: Backport [http://git.savannah.gnu.org/cgit/grub.git/commit/?id=4e9d9358e0cda6d01020005eb6343e3b69f7201a]
+
+ util/setup.c | 3 +--
+ 1 file changed, 1 insertion(+), 2 deletions(-)
+
+diff --git a/util/setup.c b/util/setup.c
+index 80363075d..9c1e1b7da 100644
+--- a/util/setup.c
++++ b/util/setup.c
+@@ -305,9 +305,8 @@ SETUP (const char *dir,
+   bl.first_block = (struct grub_boot_blocklist *) (core_img
+ 						   + GRUB_DISK_SECTOR_SIZE
+ 						   - sizeof (*bl.block));
+-  grub_util_info ("root is `%s', dest is `%s'", root, dest);
+ 
+-  grub_util_info ("Opening dest");
++  grub_util_info ("Opening dest `%s'", dest);
+   dest_dev = grub_device_open (dest);
+   if (! dest_dev)
+     grub_util_error ("%s", grub_errmsg);
+-- 
+2.17.2 (Apple Git-113)
+

meta/recipes-bsp/grub/grub2.inc

@@ -20,6 +20,7 @@ SRC_URI = "https://ftp.gnu.org/gnu/grub/grub-${PV}.tar.gz \
            file://fix.build.with.gcc-7.patch \
            file://gcc8.patch \
            file://0001-x86-64-Treat-R_X86_64_PLT32-as-R_X86_64_PC32.patch \
+           file://0001-grub-setup-Debug-message-cleanup.patch \
 "
 SRC_URI[md5sum] = "1116d1f60c840e6dbd67abbc99acb45d"
 SRC_URI[sha256sum] = "660ee136fbcee08858516ed4de2ad87068bfe1b6b8b37896ce3529ff054a726d"