[Buildroot] [PATCH] package/mmc-utils: fix build failure due to a warning and -Werror enabled

[Giulio Benetti]

Add patch to fix warning that is treated like error:
```
In function '__bswap_32',
    inlined from 'do_rpmb_write_block' at mmc_cmds.c:2293:27:
/home/autobuild/autobuild/instance-15/output-1/host/aarch64-buildroot-linux-gnu/sysroot/usr/include/bits/byteswap.h:52:10: error: 'cnt' may be used uninitialized [-Werror=maybe-uninitialized]
   52 |   return __builtin_bswap32 (__bsx);
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~
mmc_cmds.c: In function 'do_rpmb_write_block':
mmc_cmds.c:2270:22: note: 'cnt' was declared here
 2270 |         unsigned int cnt;
      |                      ^~~
cc1: all warnings being treated as errors
```
Patch is pending upstream:
https://patchwork.kernel.org/project/linux-mmc/patch/20220918124210.1127345-1-giulio.benetti@benettiengineering.com/

Fixes:
http://autobuild.buildroot.net/results/18c4fce5416e5d1ccd95900ccef87d4c045a361e/

Signed-off-by: Giulio Benetti <giulio.benetti at benettiengineering.com>
---
 ...ds.c-fix-warning-on-uninitialized-cn.patch | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 package/mmc-utils/0002-mmc-utils-mmc_cmds.c-fix-warning-on-uninitialized-cn.patch

diff --git a/package/mmc-utils/0002-mmc-utils-mmc_cmds.c-fix-warning-on-uninitialized-cn.patch b/package/mmc-utils/0002-mmc-utils-mmc_cmds.c-fix-warning-on-uninitialized-cn.patch
new file mode 100644
index 0000000000..e2f74879a6
--- /dev/null
+++ b/package/mmc-utils/0002-mmc-utils-mmc_cmds.c-fix-warning-on-uninitialized-cn.patch
@@ -0,0 +1,27 @@
+From bf783bbc2da0348591dd317ccd53bbfc5a57f2f8 Mon Sep 17 00:00:00 2001
+From: Giulio Benetti <giulio.benetti at benettiengineering.com>
+Date: Sun, 18 Sep 2022 14:10:29 +0200
+Subject: [PATCH] mmc-utils: mmc_cmds.c: fix warning on uninitialized 'cnt'
+
+Signed-off-by: Giulio Benetti <giulio.benetti at benettiengineering.com>
+[Upstream status: https://patchwork.kernel.org/project/linux-mmc/patch/20220918124210.1127345-1-giulio.benetti@benettiengineering.com/]
+---
+ mmc_cmds.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/mmc_cmds.c b/mmc_cmds.c
+index 12b7802..777d649 100644
+--- a/mmc_cmds.c
++++ b/mmc_cmds.c
+@@ -2436,7 +2436,7 @@ int do_rpmb_write_block(int nargs, char **argv)
+ 	int ret, dev_fd, key_fd, data_fd;
+ 	unsigned char key[32];
+ 	uint16_t addr;
+-	unsigned int cnt;
++	unsigned int cnt = 0;
+ 	struct rpmb_frame frame_in = {
+ 		.req_resp    = htobe16(MMC_RPMB_WRITE),
+ 		.block_count = htobe16(1)
+-- 
+2.34.1
+
-- 
2.34.1