pldm: Removing default string length

Removing default string length from BIOS json configuration
files.

String BIOS attributes defined in BIOS configuration json file
contains "default_string_length". Providing default string length
manually is error prone. As String length can be calculated and
populated easily in the code, removing json support for
default_string_length.

Tested: Power on/off
        Gtests passed.

Change-Id: I7604d8ccedd60a39ba07e1df67ff5712f31e7f6e
Signed-off-by: Archana Kakani <archana.kakani@ibm.com>
diff --git a/libpldmresponder/test/libpldmresponder_systemspecific_bios_test.cpp b/libpldmresponder/test/libpldmresponder_systemspecific_bios_test.cpp
index 6d80b9d..1b84204 100644
--- a/libpldmresponder/test/libpldmresponder_systemspecific_bios_test.cpp
+++ b/libpldmresponder/test/libpldmresponder_systemspecific_bios_test.cpp
@@ -160,11 +160,10 @@
                 EXPECT_EQ(
                     stringField.maxLength,
                     jsonEntry->at("maximum_string_length").get<uint16_t>());
-                EXPECT_EQ(
-                    stringField.defLength,
-                    jsonEntry->at("default_string_length").get<uint16_t>());
                 EXPECT_EQ(stringField.defString,
                           jsonEntry->at("default_string").get<std::string>());
+                EXPECT_EQ(stringField.defLength,
+                          (stringField.defString).length());
                 break;
             }
             case PLDM_BIOS_INTEGER: