Implement command GetDateTime

This commit implements the GetDateTime command which is
defined in PLDM Bios Control and Configuration Specification.

Change-Id: Iced21bbad7be07d357b6885b1b1e03b07a3da165
Signed-off-by: Sampa Misra <sampmisr@in.ibm.com>
diff --git a/libpldm/base.h b/libpldm/base.h
index 3673e9f..77b1045 100644
--- a/libpldm/base.h
+++ b/libpldm/base.h
@@ -16,6 +16,7 @@
 enum pldm_supported_types {
 	PLDM_BASE = 0x00,
 	PLDM_PLATFORM = 0x02,
+	PLDM_BIOS = 0x03,
 };
 
 /** @brief PLDM Commands