EmbeddedPkg/TimeBaseLib: Add function to get Week day.

This patch add function EfiTimeToWday() which returns
day of the week.
It is needed by our upcoming patches in edk2-platforms.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Vabhav Sharma <vabhav.sharma@nxp.com>
Signed-off-by: Meenakshi Aggarwal <meenakshi.aggarwal@nxp.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

EmbeddedPkg/Include/Library/TimeBaseLib.h

@@ -65,4 +65,12 @@ EfiTimeToEpoch (
   IN  EFI_TIME  *Time
   );
 
+/**
+  returns Day of the week [0-6] 0=Sunday
+ **/
+UINTN
+EfiTimeToWday (
+  IN  EFI_TIME  *Time
+  );
+
 #endif