mgmt: mcumgr: grp: os_mgmt: Add error code for invalid responses

Adds a new error code that can be used to signify that a query was
valid but the response was not valid

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>

include/zephyr/mgmt/mcumgr/grp/os_mgmt/os_mgmt.h

@@ -47,6 +47,9 @@ enum os_mgmt_err_code_t {
 
 	/** RTC command failed */
 	OS_MGMT_ERR_RTC_COMMAND_FAILED,
+
+	/** Query was recognized but there is no valid value for the response. */
+	OS_MGMT_ERR_QUERY_RESPONSE_VALUE_NOT_VALID,
 };
 
 /* Bitmask values used by the os info command handler. Note that the width of this variable is

subsys/mgmt/mcumgr/grp/os_mgmt/src/os_mgmt.c

@@ -1053,6 +1053,7 @@ static int os_mgmt_translate_error_code(uint16_t err)
 
 	case OS_MGMT_ERR_QUERY_YIELDS_NO_ANSWER:
 	case OS_MGMT_ERR_RTC_NOT_SET:
+	case OS_MGMT_ERR_QUERY_RESPONSE_VALUE_NOT_VALID:
 		rc = MGMT_ERR_ENOENT;
 		break;