documentation: Update information about Kontron mAL10

1. The video output now works correctly with Intel IGD (tested with
   TianoCore, edk2-stable201903-3392-gf7fe27d686).
2. The kempld EC driver now supports GPIO configuration since
   commit 9941e5a5e6 (ec/kontron/kempld: Add minimal GPIO driver).
3. CorebootPayloadPkg is practically dead by now, so delete the comment
   about the problem with it.

Change-Id: Ic216c3437b2670638c845ee8964f831b80e18fce
Signed-off-by: Maxim Polyakov <max.senia.poliak@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57461
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/Documentation/mainboard/kontron/mal10.md b/Documentation/mainboard/kontron/mal10.md
index b2eefc3..b349a6c 100644
--- a/Documentation/mainboard/kontron/mal10.md
+++ b/Documentation/mainboard/kontron/mal10.md
@@ -73,12 +73,6 @@
 temperature value is taken from a thermal resistor (NTC) that is placed very
 close to the CPU.
 
-## Known issues
-
-- Works only with Tianocore "UEFIPayload" payload edk2-stable201903-1569-g3e63a91
-  Booting with the "CorebootPayload" [crashes].
-- Tianocore outputs video through an external GPU only.
-
 ## Untested
 
 - IGD/LVDS
@@ -86,7 +80,7 @@
 
 ## Tested and working
 
-- Kontron CPLD/EC (Serial ports, I2C port)
+- Kontron CPLD/EC (Serial ports, I2C port, GPIOs)
 - NCT7802 [HWM](#Hardware Monitor)
 - USB2/3
 - Gigabit Ethernet ports