clearfog: kernel: really enable CONFIG_HIGHMEM

That's the risk of applying config changes by hand and never actually
verifying whether the CI-built image has that right fix -- one can have
fat fingers and insert that option to a wrong position, not noticing
that there's been a CONFIG_HIGHMEM=n at some unrelated block later on,
meaning that the config option gets overridden by "n".

So, given that kernel's own arch/arm/configs/mvebu_v7_defconfig already
sets CONFIG_HIGHMEM=y, just don't mess with it.

Fixes: ba4309e (kernel: update and enable full 1GB of RAM on Clearfog Base)
Change-Id: I0ac7c407d94c9543fbd387ffef87c8ca13ca748a
diff --git a/board/czechlight/clearfog/linux.fragment b/board/czechlight/clearfog/linux.fragment
index 71cd8bd..4010f68 100644
--- a/board/czechlight/clearfog/linux.fragment
+++ b/board/czechlight/clearfog/linux.fragment
@@ -1,6 +1,3 @@
-# enable 1GB of RAM, not just 750 MB
-CONFIG_HIGHMEM=y
-
 # this is a part of the Clearfog Base carrier
 CONFIG_SENSORS_MCP3021=y
 
@@ -42,7 +39,6 @@
 CONFIG_MACH_ARMADA_XP=n
 CONFIG_MACH_DOVE=n
 CONFIG_NR_CPUS=2
-CONFIG_HIGHMEM=n
 CONFIG_MV643XX_ETH=n
 CONFIG_KEYBOARD_ATKBD=N
 CONFIG_INPUT_MOUSE=N