package/azure-iot-sdk-c: fix build with gcc 11

package/azure-iot-sdk-c: fix build with gcc 11

Fix the following build failure with gcc 11:

/tmp/instance-7/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/c-utility/src/hmac.c:211:43: error: argument 2 of type 'uint8_t *' {aka 'unsigned char *'} declared as a pointer [-Werror=array-parameter=]
  211 | int hmacResult(HMACContext *ctx, uint8_t *digest)
      |                                  ~~~~~~~~~^~~~~~
In file included from /tmp/instance-7/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/c-utility/src/hmac.c:13:
/tmp/instance-7/output-1/build/azure-iot-sdk-c-LTS_01_2021_Ref01/c-utility/inc/azure_c_shared_utility/sha.h:252:42: note: previously declared as an array 'uint8_t[64]' {aka 'unsigned char[64]'}
  252 | int hmacResult(HMACContext *ctx, uint8_t digest[USHAMaxHashSize]);
      |                                  ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

Fixes:
 - http://autobuild.buildroot.org/results/11a6eebd0deea679683a93a5c8355d00acdfe51e

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>