PEL: Print list of PELs

PelTool commands for printing a list of PELs.

PEL list sample:

{
	"0x50000004": {
		"SRC": "BD8D1001",
		"PLID": "0x50000004",
		"CreatorID": "BMC",
		"Subsystem": "bmc_firmware",
		"Commit Time": "10/24/2019  15:50:08",
		"Sev": "unrecoverable",
 		"CompID": "0x1000"
 	}

}

Change-Id: Ifd864a6561c09de098689195edcf107b3fe550e3
Signed-off-by: Aatir <aatrapps@gmail.com>
diff --git a/extensions/openpower-pels/pel_values.cpp b/extensions/openpower-pels/pel_values.cpp
index 775c0f5..8f5c1cd 100644
--- a/extensions/openpower-pels/pel_values.cpp
+++ b/extensions/openpower-pels/pel_values.cpp
@@ -239,6 +239,19 @@
     {"S", "SLIC"},     {"B", "Hostboot"}, {"T", "OCC"},  {"M", "I/O Drawer"},
     {"K", "Sapphire"}, {"P", "PowerNV"}};
 
+std::string getValue(const uint8_t field, const pel_values::PELValues& values)
+{
+
+    auto tmp = pel_values::findByValue(field, values);
+    if (tmp != values.end())
+    {
+        return std::get<pel_values::registryNamePos>(*tmp);
+    }
+    else
+    {
+        return "invalid";
+    }
+}
 } // namespace pel_values
 } // namespace pels
 } // namespace openpower