board: sl28: enable EFI_SET_TIME support

Allow EFI to actually set the time before ExitBootServices().
Signed-off-by: NMichael Walle <michael@walle.cc>
Reviewed-by: NPriyanka Jain <priyanka.jain@nxp.com>

configs/kontron_sl28_defconfig

@@ -94,3 +94,4 @@ CONFIG_USB_XHCI_HCD=y
 CONFIG_USB_XHCI_DWC3=y
 CONFIG_OF_LIBFDT_ASSUME_MASK=0x0
 CONFIG_OF_LIBFDT_OVERLAY=y
+CONFIG_EFI_SET_TIME=y