vc/amd/agesa/f15tn: add 933 MHz to GfxMemClockFrequencyDefinitionTable

This fix is required to avoid the division-by-zero error described at
https://mail.coreboot.org/pipermail/coreboot/2014-March/077418.html
while trying to run the DDR3 memory at 1866 MT/s (933 MHz).

With this fix in place, ASUS A88XM-E boots fine with RAM at 1866 MT/s.

Signed-off-by: Mike Banon <mikebdp2@gmail.com>
Change-Id: I8e7d00e362879b1247ecf2ab828936268bf9075f
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40485
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Michał Żygowski <michal.zygowski@3mdeb.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/vendorcode/amd/agesa/f15tn/Proc/GNB/Modules/GnbInitTN/GfxLibTN.c

@@ -73,7 +73,7 @@
 CONST UINT16 GfxMemClockFrequencyDefinitionTable [][8] = {
 {0 ,  0 ,  0 ,  0 ,  333,  0,  400,  0 },
 {0 ,  0 ,  533,  0 ,  0 ,  0 ,  667,  0 },
-{0 ,  0 ,   800,  0 ,  0 ,  0 ,  0 ,  0 },
+{0 ,  0 ,   800,  0 ,  0 ,  0 , 933,  0 },
 {0 , 1050, 1066, 0 , 0,    0 , 0,    1200}
 };