mainboard: Drop abuild.disabled files for Skylake boards

Make sure the latest & greatest Intel targets actually
build in our build system.

intel/sklrvp is still failing for reasons unrelated to the rest
of the skylake boards.  Leaving that disabled for now.

Change-Id: Ie784628a57257cea30e5e47074648198b884f6db
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Signed-off-by: Martin Roth <martinroth@google.com>
Reviewed-on: https://review.coreboot.org/12857
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Tested-by: build bot (Jenkins)

src/mainboard/google/chell/abuild.disabled

@@ -1,2 +0,0 @@
-Successful builds for this board require the Skylake FSP binary and header files
-along with the Skylake microcode files from Intel.

src/mainboard/google/glados/abuild.disabled

@@ -1,2 +0,0 @@
-Successful builds for this board require the Skylake FSP binary and header files
-along with the Skylake microcode files from Intel.

src/mainboard/google/lars/abuild.disabled

@@ -1,2 +0,0 @@
-Successful builds for this board require the Skylake FSP binary and header files
-along with the Skylake microcode files from Intel.

src/mainboard/intel/kunimitsu/abuild.disabled

@@ -1,2 +0,0 @@
-Successful builds for this board require the Skylake FSP binary and header files
-along with the Skylake microcode files from Intel.